diff --git a/packages/flutter/lib/src/material/bottom_app_bar.dart b/packages/flutter/lib/src/material/bottom_app_bar.dart
index 682dc04ac0..6a05e59516 100644
--- a/packages/flutter/lib/src/material/bottom_app_bar.dart
+++ b/packages/flutter/lib/src/material/bottom_app_bar.dart
@@ -42,7 +42,7 @@ import 'theme.dart';
 class BottomAppBar extends StatefulWidget {
   /// Creates a bottom application bar.
   ///
-  /// The [clipBehavior] argument must not be null.
+  /// The [clipBehavior] argument defaults to [Clip.none] and must not be null.
   /// Additionally, [elevation] must be non-negative.
   ///
   /// If [color], [elevation], or [shape] are null, their [BottomAppBarTheme] values will be used.
@@ -56,9 +56,9 @@ class BottomAppBar extends StatefulWidget {
     this.clipBehavior = Clip.none,
     this.notchMargin = 4.0,
     this.child,
-  }) : assert(clipBehavior != null),
-       assert(elevation == null || elevation >= 0.0),
+  }) : assert(elevation == null || elevation >= 0.0),
        assert(notchMargin != null),
+       assert(clipBehavior != null),
        super(key: key);
 
   /// The widget below this widget in the tree.
@@ -92,6 +92,8 @@ class BottomAppBar extends StatefulWidget {
   final NotchedShape shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   /// The margin between the [FloatingActionButton] and the [BottomAppBar]'s
diff --git a/packages/flutter/lib/src/material/button.dart b/packages/flutter/lib/src/material/button.dart
index 95e03c5466..0fad0969ea 100644
--- a/packages/flutter/lib/src/material/button.dart
+++ b/packages/flutter/lib/src/material/button.dart
@@ -241,6 +241,8 @@ class RawMaterialButton extends StatefulWidget {
   final bool autofocus;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   @override
diff --git a/packages/flutter/lib/src/material/card.dart b/packages/flutter/lib/src/material/card.dart
index 1ff6aa04ea..0dcc45558c 100644
--- a/packages/flutter/lib/src/material/card.dart
+++ b/packages/flutter/lib/src/material/card.dart
@@ -145,6 +145,7 @@ class Card extends StatelessWidget {
   final bool borderOnForeground;
 
   /// {@macro flutter.widgets.Clip}
+  ///
   /// If this property is null then [ThemeData.cardTheme.clipBehavior] is used.
   /// If that's null then the behavior will be [Clip.none].
   final Clip clipBehavior;
@@ -177,7 +178,6 @@ class Card extends StatelessWidget {
   final Widget child;
 
   static const double _defaultElevation = 1.0;
-  static const Clip _defaultClipBehavior = Clip.none;
 
   @override
   Widget build(BuildContext context) {
@@ -195,7 +195,7 @@ class Card extends StatelessWidget {
             borderRadius: BorderRadius.all(Radius.circular(4.0)),
           ),
           borderOnForeground: borderOnForeground,
-          clipBehavior: clipBehavior ?? cardTheme.clipBehavior ?? _defaultClipBehavior,
+          clipBehavior: clipBehavior ?? cardTheme.clipBehavior ?? Clip.none,
           child: Semantics(
             explicitChildNodes: !semanticContainer,
             child: child,
diff --git a/packages/flutter/lib/src/material/chip.dart b/packages/flutter/lib/src/material/chip.dart
index 4cefe3ae35..6755cb95de 100644
--- a/packages/flutter/lib/src/material/chip.dart
+++ b/packages/flutter/lib/src/material/chip.dart
@@ -96,6 +96,8 @@ abstract class ChipAttributes {
   ShapeBorder get shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   Clip get clipBehavior;
 
   /// {@macro flutter.widgets.Focus.focusNode}
@@ -1227,6 +1229,7 @@ class ActionChip extends StatelessWidget implements ChipAttributes, TappableChip
     this.elevation,
     this.shadowColor,
   }) : assert(label != null),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        assert(
          onPressed != null,
diff --git a/packages/flutter/lib/src/material/flat_button.dart b/packages/flutter/lib/src/material/flat_button.dart
index 9dec828774..bd84a66ea0 100644
--- a/packages/flutter/lib/src/material/flat_button.dart
+++ b/packages/flutter/lib/src/material/flat_button.dart
@@ -115,12 +115,13 @@ class FlatButton extends MaterialButton {
     Brightness colorBrightness,
     EdgeInsetsGeometry padding,
     ShapeBorder shape,
-    Clip clipBehavior,
+    Clip clipBehavior = Clip.none,
     FocusNode focusNode,
     bool autofocus = false,
     MaterialTapTargetSize materialTapTargetSize,
     @required Widget child,
-  }) : assert(autofocus != null),
+  }) : assert(clipBehavior != null),
+       assert(autofocus != null),
        super(
          key: key,
          onPressed: onPressed,
@@ -196,7 +197,7 @@ class FlatButton extends MaterialButton {
       padding: buttonTheme.getPadding(this),
       constraints: buttonTheme.getConstraints(this),
       shape: buttonTheme.getShape(this),
-      clipBehavior: clipBehavior ?? Clip.none,
+      clipBehavior: clipBehavior,
       focusNode: focusNode,
       autofocus: autofocus,
       materialTapTargetSize: buttonTheme.getMaterialTapTargetSize(this),
@@ -227,7 +228,7 @@ class _FlatButtonWithIcon extends FlatButton with MaterialButtonWithIconMixin {
     Brightness colorBrightness,
     EdgeInsetsGeometry padding,
     ShapeBorder shape,
-    Clip clipBehavior,
+    Clip clipBehavior = Clip.none,
     FocusNode focusNode,
     bool autofocus = false,
     MaterialTapTargetSize materialTapTargetSize,
@@ -235,6 +236,7 @@ class _FlatButtonWithIcon extends FlatButton with MaterialButtonWithIconMixin {
     @required Widget label,
   }) : assert(icon != null),
        assert(label != null),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        super(
          key: key,
diff --git a/packages/flutter/lib/src/material/floating_action_button.dart b/packages/flutter/lib/src/material/floating_action_button.dart
index 31f32ede96..4910f95235 100644
--- a/packages/flutter/lib/src/material/floating_action_button.dart
+++ b/packages/flutter/lib/src/material/floating_action_button.dart
@@ -122,7 +122,7 @@ class _DefaultHeroTag {
 class FloatingActionButton extends StatelessWidget {
   /// Creates a circular floating action button.
   ///
-  /// The [mini] and [clipBehavior] arguments must be non-null. Additionally,
+  /// The [mini] and [clipBehavior] arguments must not be null. Additionally,
   /// [elevation], [highlightElevation], and [disabledElevation] (if specified)
   /// must be non-negative.
   const FloatingActionButton({
@@ -154,6 +154,7 @@ class FloatingActionButton extends StatelessWidget {
        assert(highlightElevation == null || highlightElevation >= 0.0),
        assert(disabledElevation == null || disabledElevation >= 0.0),
        assert(mini != null),
+       assert(clipBehavior != null),
        assert(isExtended != null),
        assert(autofocus != null),
        _sizeConstraints = mini ? _kMiniSizeConstraints : _kSizeConstraints,
@@ -162,7 +163,7 @@ class FloatingActionButton extends StatelessWidget {
   /// Creates a wider [StadiumBorder]-shaped floating action button with
   /// an optional [icon] and a [label].
   ///
-  /// The [label], [autofocus], and [clipBehavior] arguments must non-null.
+  /// The [label], [autofocus], and [clipBehavior] arguments must not be null.
   /// Additionally, [elevation], [highlightElevation], and [disabledElevation]
   /// (if specified) must be non-negative.
   FloatingActionButton.extended({
@@ -194,6 +195,7 @@ class FloatingActionButton extends StatelessWidget {
        assert(highlightElevation == null || highlightElevation >= 0.0),
        assert(disabledElevation == null || disabledElevation >= 0.0),
        assert(isExtended != null),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        _sizeConstraints = _kExtendedSizeConstraints,
        mini = false,
@@ -363,6 +365,8 @@ class FloatingActionButton extends StatelessWidget {
   final ShapeBorder shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   /// True if this is an "extended" floating action button.
@@ -463,7 +467,7 @@ class FloatingActionButton extends StatelessWidget {
       splashColor: splashColor,
       textStyle: textStyle,
       shape: shape,
-      clipBehavior: clipBehavior ?? Clip.none,
+      clipBehavior: clipBehavior,
       focusNode: focusNode,
       autofocus: autofocus,
       child: child,
diff --git a/packages/flutter/lib/src/material/material.dart b/packages/flutter/lib/src/material/material.dart
index 293d1fc52b..3ef5c75391 100644
--- a/packages/flutter/lib/src/material/material.dart
+++ b/packages/flutter/lib/src/material/material.dart
@@ -157,9 +157,9 @@ abstract class MaterialInkController {
 class Material extends StatefulWidget {
   /// Creates a piece of material.
   ///
-  /// The [type], [elevation], [shadowColor], [borderOnForeground] and
-  /// [animationDuration] arguments must not be null. Additionally, [elevation]
-  /// must be non-negative.
+  /// The [type], [elevation], [shadowColor], [borderOnForeground],
+  /// [clipBehavior], and [animationDuration] arguments must not be null.
+  /// Additionally, [elevation] must be non-negative.
   ///
   /// If a [shape] is specified, then the [borderRadius] property must be
   /// null and the [type] property must not be [MaterialType.circle]. If the
@@ -185,8 +185,8 @@ class Material extends StatefulWidget {
        assert(!(shape != null && borderRadius != null)),
        assert(animationDuration != null),
        assert(!(identical(type, MaterialType.circle) && (borderRadius != null || shape != null))),
-       assert(clipBehavior != null),
        assert(borderOnForeground != null),
+       assert(clipBehavior != null),
        super(key: key);
 
   /// The widget below this widget in the tree.
@@ -264,6 +264,8 @@ class Material extends StatefulWidget {
   /// See the enum [Clip] for details of all possible options and their common
   /// use cases.
   /// {@endtemplate}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   /// Defines the duration of animated changes for [shape], [elevation],
@@ -670,6 +672,11 @@ class ShapeBorderTween extends Tween<ShapeBorder> {
 ///
 /// Animates [elevation], [shadowColor], and [shape].
 class _MaterialInterior extends ImplicitlyAnimatedWidget {
+  /// Creates a const instance of [_MaterialInterior].
+  ///
+  /// The [child], [shape], [clipBehavior], [color], and [shadowColor] arguments
+  /// must not be null. The [elevation] must be specified and greater than or
+  /// equal to zero.
   const _MaterialInterior({
     Key key,
     @required this.child,
@@ -707,6 +714,8 @@ class _MaterialInterior extends ImplicitlyAnimatedWidget {
   final bool borderOnForeground;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   /// The target z-coordinate at which to place this physical object relative
diff --git a/packages/flutter/lib/src/material/material_button.dart b/packages/flutter/lib/src/material/material_button.dart
index 600050a070..461b20dbec 100644
--- a/packages/flutter/lib/src/material/material_button.dart
+++ b/packages/flutter/lib/src/material/material_button.dart
@@ -77,7 +77,8 @@ class MaterialButton extends StatelessWidget {
     this.minWidth,
     this.height,
     this.child,
-  }) : assert(autofocus != null),
+  }) : assert(clipBehavior != null),
+       assert(autofocus != null),
        assert(elevation == null || elevation >= 0.0),
        assert(focusElevation == null || focusElevation >= 0.0),
        assert(hoverElevation == null || hoverElevation >= 0.0),
@@ -306,6 +307,8 @@ class MaterialButton extends StatelessWidget {
   final ShapeBorder shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none], and must not be null.
   final Clip clipBehavior;
 
   /// {@macro flutter.widgets.Focus.focusNode}
@@ -362,7 +365,7 @@ class MaterialButton extends StatelessWidget {
         minHeight: height,
       ),
       shape: buttonTheme.getShape(this),
-      clipBehavior: clipBehavior ?? Clip.none,
+      clipBehavior: clipBehavior,
       focusNode: focusNode,
       animationDuration: buttonTheme.getAnimationDuration(this),
       child: child,
diff --git a/packages/flutter/lib/src/material/outline_button.dart b/packages/flutter/lib/src/material/outline_button.dart
index fda1ab961b..4e672d12da 100644
--- a/packages/flutter/lib/src/material/outline_button.dart
+++ b/packages/flutter/lib/src/material/outline_button.dart
@@ -75,11 +75,12 @@ class OutlineButton extends MaterialButton {
     this.highlightedBorderColor,
     EdgeInsetsGeometry padding,
     ShapeBorder shape,
-    Clip clipBehavior,
+    Clip clipBehavior = Clip.none,
     FocusNode focusNode,
     bool autofocus = false,
     Widget child,
   }) : assert(highlightElevation == null || highlightElevation >= 0.0),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        super(
          key: key,
@@ -220,12 +221,13 @@ class _OutlineButtonWithIcon extends OutlineButton with MaterialButtonWithIconMi
     BorderSide borderSide,
     EdgeInsetsGeometry padding,
     ShapeBorder shape,
-    Clip clipBehavior,
+    Clip clipBehavior = Clip.none,
     FocusNode focusNode,
     bool autofocus = false,
     @required Widget icon,
     @required Widget label,
   }) : assert(highlightElevation == null || highlightElevation >= 0.0),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        assert(icon != null),
        assert(label != null),
@@ -279,12 +281,13 @@ class _OutlineButton extends StatefulWidget {
     @required this.highlightedBorderColor,
     this.padding,
     this.shape,
-    this.clipBehavior,
+    this.clipBehavior = Clip.none,
     this.focusNode,
     this.autofocus = false,
     this.child,
   }) : assert(highlightElevation != null && highlightElevation >= 0.0),
        assert(highlightedBorderColor != null),
+       assert(clipBehavior != null),
        assert(autofocus != null),
        super(key: key);
 
diff --git a/packages/flutter/lib/src/material/raised_button.dart b/packages/flutter/lib/src/material/raised_button.dart
index dfb4cc5c4b..17cd6f60ab 100644
--- a/packages/flutter/lib/src/material/raised_button.dart
+++ b/packages/flutter/lib/src/material/raised_button.dart
@@ -126,7 +126,7 @@ class RaisedButton extends MaterialButton {
     double disabledElevation,
     EdgeInsetsGeometry padding,
     ShapeBorder shape,
-    Clip clipBehavior,
+    Clip clipBehavior = Clip.none,
     FocusNode focusNode,
     bool autofocus = false,
     MaterialTapTargetSize materialTapTargetSize,
@@ -138,6 +138,7 @@ class RaisedButton extends MaterialButton {
        assert(hoverElevation == null || hoverElevation >= 0.0),
        assert(highlightElevation == null || highlightElevation >= 0.0),
        assert(disabledElevation == null || disabledElevation >= 0.0),
+       assert(clipBehavior != null),
        super(
          key: key,
          onPressed: onPressed,
@@ -209,7 +210,7 @@ class RaisedButton extends MaterialButton {
     return RawMaterialButton(
       onPressed: onPressed,
       onHighlightChanged: onHighlightChanged,
-      clipBehavior: clipBehavior ?? Clip.none,
+      clipBehavior: clipBehavior,
       fillColor: buttonTheme.getFillColor(this),
       textStyle: theme.textTheme.button.copyWith(color: buttonTheme.getTextColor(this)),
       focusColor: buttonTheme.getFocusColor(this),
@@ -276,6 +277,7 @@ class _RaisedButtonWithIcon extends RaisedButton with MaterialButtonWithIconMixi
   }) : assert(elevation == null || elevation >= 0.0),
        assert(highlightElevation == null || highlightElevation >= 0.0),
        assert(disabledElevation == null || disabledElevation >= 0.0),
+       assert(clipBehavior != null),
        assert(icon != null),
        assert(label != null),
        assert(autofocus != null),
diff --git a/packages/flutter/lib/src/rendering/layer.dart b/packages/flutter/lib/src/rendering/layer.dart
index 32c324d0db..8321b0f927 100644
--- a/packages/flutter/lib/src/rendering/layer.dart
+++ b/packages/flutter/lib/src/rendering/layer.dart
@@ -1058,8 +1058,10 @@ class OffsetLayer extends ContainerLayer {
 class ClipRectLayer extends ContainerLayer {
   /// Creates a layer with a rectangular clip.
   ///
-  /// The [clipRect] and [clipBehavior] properties must be non-null before the
-  /// compositing phase of the pipeline.
+  /// The [clipRect] argument must not be null before the compositing phase of
+  /// the pipeline.
+  ///
+  /// The [clipBehavior] argument must not be null, and must not be [Clip.none].
   ClipRectLayer({
     Rect clipRect,
     Clip clipBehavior = Clip.hardEdge,
@@ -1082,10 +1084,12 @@ class ClipRectLayer extends ContainerLayer {
   }
 
   /// {@template flutter.clipper.clipBehavior}
-  /// Controls how to clip (defaults to [Clip.hardEdge]).
+  /// Controls how to clip.
   ///
-  /// [Clip.none] is not allowed here.
+  /// Must not be set to null or [Clip.none].
   /// {@endtemplate}
+  ///
+  /// Defaults to [Clip.hardEdge].
   Clip get clipBehavior => _clipBehavior;
   Clip _clipBehavior;
   set clipBehavior(Clip value) {
@@ -1170,6 +1174,8 @@ class ClipRRectLayer extends ContainerLayer {
   }
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.antiAlias].
   Clip get clipBehavior => _clipBehavior;
   Clip _clipBehavior;
   set clipBehavior(Clip value) {
@@ -1254,6 +1260,8 @@ class ClipPathLayer extends ContainerLayer {
   }
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.antiAlias].
   Clip get clipBehavior => _clipBehavior;
   Clip _clipBehavior;
   set clipBehavior(Clip value) {
diff --git a/packages/flutter/lib/src/rendering/proxy_box.dart b/packages/flutter/lib/src/rendering/proxy_box.dart
index 308ec1f3a4..a54c7d94f4 100644
--- a/packages/flutter/lib/src/rendering/proxy_box.dart
+++ b/packages/flutter/lib/src/rendering/proxy_box.dart
@@ -1285,12 +1285,14 @@ class RenderClipRect extends _RenderCustomClip<Rect> {
   /// If [clipper] is null, the clip will match the layout size and position of
   /// the child.
   ///
-  /// The [clipBehavior] cannot be [Clip.none].
+  /// The [clipBehavior] must not be null or [Clip.none].
   RenderClipRect({
     RenderBox child,
     CustomClipper<Rect> clipper,
     Clip clipBehavior = Clip.antiAlias,
-  }) : super(child: child, clipper: clipper, clipBehavior: clipBehavior);
+  }) : assert(clipBehavior != null),
+       assert(clipBehavior != Clip.none),
+       super(child: child, clipper: clipper, clipBehavior: clipBehavior);
 
   @override
   Rect get _defaultClip => Offset.zero & size;
@@ -1342,13 +1344,14 @@ class RenderClipRRect extends _RenderCustomClip<RRect> {
   ///
   /// If [clipper] is non-null, then [borderRadius] is ignored.
   ///
-  /// The [clipBehavior] cannot be [Clip.none].
+  /// The [clipBehavior] argument must not be null or [Clip.none].
   RenderClipRRect({
     RenderBox child,
     BorderRadius borderRadius = BorderRadius.zero,
     CustomClipper<RRect> clipper,
     Clip clipBehavior = Clip.antiAlias,
-  }) : assert(clipBehavior != Clip.none),
+  }) : assert(clipBehavior != null),
+       assert(clipBehavior != Clip.none),
        _borderRadius = borderRadius,
        super(child: child, clipper: clipper, clipBehavior: clipBehavior) {
     assert(_borderRadius != null || clipper != null);
@@ -1418,12 +1421,13 @@ class RenderClipOval extends _RenderCustomClip<Rect> {
   /// If [clipper] is null, the oval will be inscribed into the layout size and
   /// position of the child.
   ///
-  /// The [clipBehavior] cannot be [Clip.none].
+  /// The [clipBehavior] argument must not be null or [Clip.none].
   RenderClipOval({
     RenderBox child,
     CustomClipper<Rect> clipper,
     Clip clipBehavior = Clip.antiAlias,
-  }) : assert(clipBehavior != Clip.none),
+  }) : assert(clipBehavior != null),
+       assert(clipBehavior != Clip.none),
        super(child: child, clipper: clipper, clipBehavior: clipBehavior);
 
   Rect _cachedRect;
@@ -1496,12 +1500,13 @@ class RenderClipPath extends _RenderCustomClip<Path> {
   /// consider using a [RenderClipRect], which can achieve the same effect more
   /// efficiently.
   ///
-  /// The [clipBehavior] cannot be [Clip.none].
+  /// The [clipBehavior] argument must not be null or [Clip.none].
   RenderClipPath({
     RenderBox child,
     CustomClipper<Path> clipper,
     Clip clipBehavior = Clip.antiAlias,
-  }) : assert(clipBehavior != Clip.none),
+  }) : assert(clipBehavior != null),
+       assert(clipBehavior != Clip.none),
        super(child: child, clipper: clipper, clipBehavior: clipBehavior);
 
   @override
@@ -1632,8 +1637,9 @@ class RenderPhysicalModel extends _RenderPhysicalModelBase<RRect> {
   ///
   /// The [color] is required.
   ///
-  /// The [shape], [elevation], [color], and [shadowColor] must not be null.
-  /// Additionally, the [elevation] must be non-negative.
+  /// The [shape], [elevation], [color], [clipBehavior], and [shadowColor]
+  /// arguments must not be null. Additionally, the [elevation] must be
+  /// non-negative.
   RenderPhysicalModel({
     RenderBox child,
     BoxShape shape = BoxShape.rectangle,
diff --git a/packages/flutter/lib/src/widgets/basic.dart b/packages/flutter/lib/src/widgets/basic.dart
index c06e93cb06..d606c958a8 100644
--- a/packages/flutter/lib/src/widgets/basic.dart
+++ b/packages/flutter/lib/src/widgets/basic.dart
@@ -582,19 +582,29 @@ class ClipRect extends SingleChildRenderObjectWidget {
   ///
   /// If [clipper] is null, the clip will match the layout size and position of
   /// the child.
-  const ClipRect({ Key key, this.clipper, this.clipBehavior = Clip.hardEdge, Widget child }) : super(key: key, child: child);
+  ///
+  /// The [clipBehavior] argument must not be null or [Clip.none].
+  const ClipRect({ Key key, this.clipper, this.clipBehavior = Clip.hardEdge, Widget child })
+      : assert(clipBehavior != null),
+        super(key: key, child: child);
 
   /// If non-null, determines which clip to use.
   final CustomClipper<Rect> clipper;
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.hardEdge].
   final Clip clipBehavior;
 
   @override
-  RenderClipRect createRenderObject(BuildContext context) => RenderClipRect(clipper: clipper, clipBehavior: clipBehavior);
+  RenderClipRect createRenderObject(BuildContext context) {
+    assert(clipBehavior != Clip.none);
+    return RenderClipRect(clipper: clipper, clipBehavior: clipBehavior);
+  }
 
   @override
   void updateRenderObject(BuildContext context, RenderClipRect renderObject) {
+    assert(clipBehavior != Clip.none);
     renderObject
       ..clipper = clipper
       ..clipBehavior = clipBehavior;
@@ -633,6 +643,8 @@ class ClipRRect extends SingleChildRenderObjectWidget {
   /// right-angled corners.
   ///
   /// If [clipper] is non-null, then [borderRadius] is ignored.
+  ///
+  /// The [clipBehavior] argument must not be null or [Clip.none].
   const ClipRRect({
     Key key,
     this.borderRadius,
@@ -655,13 +667,19 @@ class ClipRRect extends SingleChildRenderObjectWidget {
   final CustomClipper<RRect> clipper;
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.antiAlias].
   final Clip clipBehavior;
 
   @override
-  RenderClipRRect createRenderObject(BuildContext context) => RenderClipRRect(borderRadius: borderRadius, clipper: clipper, clipBehavior: clipBehavior);
+  RenderClipRRect createRenderObject(BuildContext context) {
+    assert(clipBehavior != Clip.none);
+    return RenderClipRRect(borderRadius: borderRadius, clipper: clipper, clipBehavior: clipBehavior);
+  }
 
   @override
   void updateRenderObject(BuildContext context, RenderClipRRect renderObject) {
+    assert(clipBehavior != Clip.none);
     renderObject
       ..borderRadius = borderRadius
       ..clipBehavior = clipBehavior
@@ -693,7 +711,11 @@ class ClipOval extends SingleChildRenderObjectWidget {
   ///
   /// If [clipper] is null, the oval will be inscribed into the layout size and
   /// position of the child.
-  const ClipOval({ Key key, this.clipper, this.clipBehavior = Clip.antiAlias, Widget child }) : super(key: key, child: child);
+  ///
+  /// The [clipBehavior] argument must not be null or [Clip.none].
+  const ClipOval({Key key, this.clipper, this.clipBehavior = Clip.antiAlias, Widget child})
+      : assert(clipBehavior != null),
+        super(key: key, child: child);
 
   /// If non-null, determines which clip to use.
   ///
@@ -707,13 +729,19 @@ class ClipOval extends SingleChildRenderObjectWidget {
   final CustomClipper<Rect> clipper;
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.antiAlias].
   final Clip clipBehavior;
 
   @override
-  RenderClipOval createRenderObject(BuildContext context) => RenderClipOval(clipper: clipper, clipBehavior: clipBehavior);
+  RenderClipOval createRenderObject(BuildContext context) {
+    assert(clipBehavior != Clip.none);
+    return RenderClipOval(clipper: clipper, clipBehavior: clipBehavior);
+  }
 
   @override
   void updateRenderObject(BuildContext context, RenderClipOval renderObject) {
+    assert(clipBehavior != Clip.none);
     renderObject
       ..clipper = clipper
       ..clipBehavior = clipBehavior;
@@ -754,12 +782,15 @@ class ClipPath extends SingleChildRenderObjectWidget {
   /// size and location of the child. However, rather than use this default,
   /// consider using a [ClipRect], which can achieve the same effect more
   /// efficiently.
+  ///
+  /// The [clipBehavior] argument must not be null or [Clip.none].
   const ClipPath({
     Key key,
     this.clipper,
     this.clipBehavior = Clip.antiAlias,
     Widget child,
-  }) : super(key: key, child: child);
+  }) : assert(clipBehavior != null),
+       super(key: key, child: child);
 
   /// Creates a shape clip.
   ///
@@ -771,6 +802,8 @@ class ClipPath extends SingleChildRenderObjectWidget {
     Clip clipBehavior = Clip.antiAlias,
     Widget child,
   }) {
+    assert(clipBehavior != null);
+    assert(clipBehavior != Clip.none);
     assert(shape != null);
     return Builder(
       key: key,
@@ -795,13 +828,19 @@ class ClipPath extends SingleChildRenderObjectWidget {
   final CustomClipper<Path> clipper;
 
   /// {@macro flutter.clipper.clipBehavior}
+  ///
+  /// Defaults to [Clip.antiAlias].
   final Clip clipBehavior;
 
   @override
-  RenderClipPath createRenderObject(BuildContext context) => RenderClipPath(clipper: clipper, clipBehavior: clipBehavior);
+  RenderClipPath createRenderObject(BuildContext context) {
+    assert(clipBehavior != Clip.none);
+    return RenderClipPath(clipper: clipper, clipBehavior: clipBehavior);
+  }
 
   @override
   void updateRenderObject(BuildContext context, RenderClipPath renderObject) {
+    assert(clipBehavior != Clip.none);
     renderObject
       ..clipper = clipper
       ..clipBehavior = clipBehavior;
@@ -838,8 +877,8 @@ class PhysicalModel extends SingleChildRenderObjectWidget {
   ///
   /// The [color] is required; physical things have a color.
   ///
-  /// The [shape], [elevation], [color], and [shadowColor] must not be null.
-  /// Additionally, the [elevation] must be non-negative.
+  /// The [shape], [elevation], [color], [clipBehavior], and [shadowColor] must
+  /// not be null. Additionally, the [elevation] must be non-negative.
   const PhysicalModel({
     Key key,
     this.shape = BoxShape.rectangle,
@@ -853,12 +892,15 @@ class PhysicalModel extends SingleChildRenderObjectWidget {
        assert(elevation != null && elevation >= 0.0),
        assert(color != null),
        assert(shadowColor != null),
+       assert(clipBehavior != null),
        super(key: key, child: child);
 
   /// The type of shape.
   final BoxShape shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   /// The border radius of the rounded corners.
@@ -931,8 +973,8 @@ class PhysicalShape extends SingleChildRenderObjectWidget {
   ///
   /// The [color] is required; physical things have a color.
   ///
-  /// The [clipper], [elevation], [color], and [shadowColor] must not be null.
-  /// Additionally, the [elevation] must be non-negative.
+  /// The [clipper], [elevation], [color], [clipBehavior], and [shadowColor]
+  /// must not be null. Additionally, the [elevation] must be non-negative.
   const PhysicalShape({
     Key key,
     @required this.clipper,
@@ -956,6 +998,8 @@ class PhysicalShape extends SingleChildRenderObjectWidget {
   final CustomClipper<Path> clipper;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   /// The z-coordinate relative to the parent at which to place this physical
diff --git a/packages/flutter/lib/src/widgets/implicit_animations.dart b/packages/flutter/lib/src/widgets/implicit_animations.dart
index 0667368604..4631ce4718 100644
--- a/packages/flutter/lib/src/widgets/implicit_animations.dart
+++ b/packages/flutter/lib/src/widgets/implicit_animations.dart
@@ -1450,9 +1450,9 @@ class _AnimatedDefaultTextStyleState extends AnimatedWidgetBaseState<AnimatedDef
 class AnimatedPhysicalModel extends ImplicitlyAnimatedWidget {
   /// Creates a widget that animates the properties of a [PhysicalModel].
   ///
-  /// The [child], [shape], [borderRadius], [elevation], [color], [shadowColor], [curve], and
-  /// [duration] arguments must not be null. Additionally, [elevation] must be
-  /// non-negative.
+  /// The [child], [shape], [borderRadius], [elevation], [color], [shadowColor],
+  /// [curve], [clipBehavior], and [duration] arguments must not be null.
+  /// Additionally, [elevation] must be non-negative.
   ///
   /// Animating [color] is optional and is controlled by the [animateColor] flag.
   ///
@@ -1492,6 +1492,8 @@ class AnimatedPhysicalModel extends ImplicitlyAnimatedWidget {
   final BoxShape shape;
 
   /// {@macro flutter.widgets.Clip}
+  ///
+  /// Defaults to [Clip.none].
   final Clip clipBehavior;
 
   /// The target border radius of the rounded corners for a rectangle shape.
diff --git a/packages/flutter/test/material/card_test.dart b/packages/flutter/test/material/card_test.dart
index 0e9e73c99e..e021d450fc 100644
--- a/packages/flutter/test/material/card_test.dart
+++ b/packages/flutter/test/material/card_test.dart
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/painting.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
@@ -171,4 +172,19 @@ void main() {
     await tester.pumpWidget(const Card(clipBehavior: Clip.antiAlias));
     expect(tester.widget<Material>(find.byType(Material)).clipBehavior, Clip.antiAlias);
   });
+
+  testWidgets('Card clipBehavior property defers to theme when null', (WidgetTester tester) async {
+    await tester.pumpWidget(Builder(builder: (BuildContext context) {
+      final ThemeData themeData = Theme.of(context);
+      return Theme(
+        data: themeData.copyWith(
+          cardTheme: themeData.cardTheme.copyWith(
+            clipBehavior: Clip.antiAliasWithSaveLayer,
+          ),
+        ),
+        child: const Card(clipBehavior: null),
+      );
+    }));
+    expect(tester.widget<Material>(find.byType(Material)).clipBehavior, Clip.antiAliasWithSaveLayer);
+  });
 }
diff --git a/packages/flutter/test/material/material_test.dart b/packages/flutter/test/material/material_test.dart
index d3afca7086..2cc7f826e1 100644
--- a/packages/flutter/test/material/material_test.dart
+++ b/packages/flutter/test/material/material_test.dart
@@ -300,6 +300,22 @@ void main() {
       expect(find.byKey(materialKey), hasNoImmediateClip);
     });
 
+    testWidgets('Null clipBehavior asserts', (WidgetTester tester) async {
+      final GlobalKey materialKey = GlobalKey();
+      Future<void> doPump() async {
+        await tester.pumpWidget(
+            Material(
+              key: materialKey,
+              type: MaterialType.transparency,
+              child: const SizedBox(width: 100.0, height: 100.0),
+              clipBehavior: null,
+            )
+        );
+      }
+
+      expect(() async => doPump(), throwsAssertionError);
+    });
+
     testWidgets('clips to bounding rect by default given Clip.antiAlias', (WidgetTester tester) async {
       final GlobalKey materialKey = GlobalKey();
       await tester.pumpWidget(