diff --git a/packages/exo/src/exo-tools.js b/packages/exo/src/exo-tools.js
index ed0089170d..6090a6ab3f 100644
--- a/packages/exo/src/exo-tools.js
+++ b/packages/exo/src/exo-tools.js
@@ -6,11 +6,11 @@ import {
   mustMatch,
   M,
   isAwaitArgGuard,
+  isRawValueGuard,
   getAwaitArgGuardPayload,
   getMethodGuardPayload,
   getInterfaceGuardPayload,
   getCopyMapEntries,
-  // isRawValueGuard,
 } from '@endo/patterns';
 
 /** @typedef {import('@endo/patterns').Method} Method */
@@ -30,7 +30,9 @@ const { defineProperties, fromEntries } = Object;
  * A method guard, for inclusion in an interface guard, that does not
  * enforce any constraints of incoming arguments or return results.
  */
-// const RawMethodGuard = M.call().rest(M.rawValue()).returns(M.rawValue());
+const RawMethodGuard = M.call().rest(M.rawValue()).returns(M.rawValue());
+
+const REDACTED_RAW_VALUE = '<redacted rawValue>';
 
 /**
  * A method guard, for inclusion in an interface guard, that enforces only that
@@ -39,28 +41,59 @@ const { defineProperties, fromEntries } = Object;
  * enforcement for a method guard, and is implied by all other
  * non-raw method guards.
  */
-const MinMethodGuard = M.call().rest(M.any()).returns(M.any());
+const PassableMethodGuard = M.call().rest(M.any()).returns(M.any());
+
+/**
+ * @typedef {object} RedactConfig
+ * @property {number} declaredLen
+ * @property {boolean} hasRestArgGuard
+ * @property {boolean} needRedaction
+ * @property {Pattern} paramsPattern
+ * @property {boolean} rawRestArgs
+ * @property {number[]} redactedIndices
+ */
 
 /**
  * @param {Passable[]} syncArgs
- * @param {MethodGuardPayload} methodGuardPayload
+ * @param {RedactConfig} redactConfig
  * @param {string} [label]
  * @returns {Passable[]} Returns the args that should be passed to the
  * raw method
  */
-const defendSyncArgs = (syncArgs, methodGuardPayload, label = undefined) => {
-  const { argGuards, optionalArgGuards, restArgGuard } = methodGuardPayload;
-  const paramsPattern = M.splitArray(
-    argGuards,
-    optionalArgGuards,
-    restArgGuard,
-  );
-  mustMatch(harden(syncArgs), paramsPattern, label);
-  if (restArgGuard !== undefined) {
+const defendSyncArgs = (syncArgs, redactConfig, label = undefined) => {
+  const {
+    declaredLen,
+    hasRestArgGuard,
+    needRedaction,
+    paramsPattern,
+    rawRestArgs,
+    redactedIndices,
+  } = redactConfig;
+
+  // Only manipulate the original args if our params pattern didn't contain any
+  // raw values.
+  let redactedArgs = syncArgs;
+  if (rawRestArgs) {
+    // Don't harden the rest args.
+    redactedArgs = syncArgs.slice(0, Math.min(syncArgs.length, declaredLen));
+  } else if (needRedaction) {
+    // Copy the arguments array, avoiding hardening the redacted ones (which are
+    // trivially matched).
+    redactedArgs = [...syncArgs];
+  }
+
+  for (const i of redactedIndices) {
+    if (i >= redactedArgs.length) {
+      break;
+    }
+    redactedArgs[i] = REDACTED_RAW_VALUE;
+  }
+
+  mustMatch(harden(redactedArgs), paramsPattern, label);
+
+  if (hasRestArgGuard) {
     return syncArgs;
   }
-  const declaredLen =
-    argGuards.length + (optionalArgGuards ? optionalArgGuards.length : 0);
   if (syncArgs.length <= declaredLen) {
     return syncArgs;
   }
@@ -68,6 +101,60 @@ const defendSyncArgs = (syncArgs, methodGuardPayload, label = undefined) => {
   return syncArgs.slice(0, declaredLen);
 };
 
+/**
+ * @param {MethodGuardPayload} methodGuardPayload
+ */
+const redactRawValues = methodGuardPayload => {
+  const {
+    argGuards,
+    optionalArgGuards = [],
+    restArgGuard,
+  } = methodGuardPayload;
+
+  const rawArgGuards = [...argGuards, ...optionalArgGuards];
+
+  let needRedaction = false;
+
+  const redactedIndices = [];
+  for (let i = 0; i < rawArgGuards.length; i += 1) {
+    if (isRawValueGuard(rawArgGuards[i])) {
+      rawArgGuards[i] = REDACTED_RAW_VALUE;
+      redactedIndices.push(i);
+      needRedaction = true;
+    }
+  }
+
+  // Always match the redacted args if there is a raw rest that applies.
+  let rawRestArgGuard = restArgGuard;
+  let rawRestArgs = false;
+  if (isRawValueGuard(rawRestArgGuard)) {
+    rawRestArgGuard = undefined;
+    rawRestArgs = true;
+  }
+  const redactedMethodGuardPayload = harden({
+    ...methodGuardPayload,
+    argGuards: rawArgGuards.slice(0, argGuards.length),
+    optionalArgGuards: rawArgGuards.slice(argGuards.length),
+    restArgGuard: rawRestArgGuard,
+  });
+
+  const paramsPattern = M.splitArray(
+    redactedMethodGuardPayload.argGuards,
+    redactedMethodGuardPayload.optionalArgGuards,
+    redactedMethodGuardPayload.restArgGuard,
+  );
+
+  return harden({
+    declaredLen: rawArgGuards.length,
+    hasRestArgGuard: restArgGuard !== undefined,
+    needRedaction,
+    paramsPattern,
+    rawRestArgs,
+    redactedIndices,
+    redactedMethodGuardPayload,
+  });
+};
+
 /**
  * @param {Method} method
  * @param {MethodGuardPayload} methodGuardPayload
@@ -76,16 +163,15 @@ const defendSyncArgs = (syncArgs, methodGuardPayload, label = undefined) => {
  */
 const defendSyncMethod = (method, methodGuardPayload, label) => {
   const { returnGuard } = methodGuardPayload;
+  const isRawReturn = isRawValueGuard(returnGuard);
+  const redactConfig = redactRawValues(methodGuardPayload);
   const { syncMethod } = {
     // Note purposeful use of `this` and concise method syntax
     syncMethod(...syncArgs) {
-      const realArgs = defendSyncArgs(
-        harden(syncArgs),
-        methodGuardPayload,
-        label,
-      );
+      // Only harden args and return value if not dealing with a raw value guard.
+      const realArgs = defendSyncArgs(syncArgs, redactConfig, label);
       const result = apply(method, this, realArgs);
-      mustMatch(harden(result), returnGuard, `${label}: result`);
+      isRawReturn || mustMatch(harden(result), returnGuard, `${label}: result`);
       return result;
     },
   };
@@ -193,6 +279,7 @@ const defendMethod = (method, methodGuard, label) => {
  * @param {CallableFunction} behaviorMethod
  * @param {boolean} [thisfulMethods]
  * @param {MethodGuard} [methodGuard]
+ * @param {import('@endo/patterns').DefaultGuardType} [defaultGuards]
  */
 const bindMethod = (
   methodTag,
@@ -200,6 +287,7 @@ const bindMethod = (
   behaviorMethod,
   thisfulMethods = false,
   methodGuard = undefined,
+  defaultGuards = 'never',
 ) => {
   assert.typeof(behaviorMethod, 'function');
 
@@ -235,12 +323,23 @@ const bindMethod = (
           return apply(behaviorMethod, null, [context, ...args]);
         },
       };
+  if (!methodGuard && thisfulMethods) {
+    switch (defaultGuards) {
+      case 'never':
+      case 'passable':
+        methodGuard = PassableMethodGuard;
+        break;
+      case 'raw':
+        methodGuard = RawMethodGuard;
+        break;
+      default:
+        throw Fail`Unrecognized defaultGuards ${q(defaultGuards)}`;
+    }
+  }
   if (methodGuard) {
     method = defendMethod(method, methodGuard, methodTag);
-  } else if (thisfulMethods) {
-    // For far classes ensure that inputs and outputs are passable.
-    method = defendMethod(method, MinMethodGuard, methodTag);
   }
+
   defineProperties(method, {
     name: { value: methodTag },
     length: {
@@ -303,18 +402,22 @@ export const defendPrototype = (
   }
   /** @type {Record<PropertyKey, MethodGuard> | undefined} */
   let methodGuards;
+  /** @type {import('@endo/patterns').DefaultGuardType} */
+  let defaultGuards = 'never';
   if (interfaceGuard) {
     const {
       interfaceName,
       methodGuards: mg,
       symbolMethodGuards,
-      defaultGuards,
+      sloppy,
+      defaultGuards: dg = sloppy ? 'passable' : defaultGuards,
     } = getInterfaceGuardPayload(interfaceGuard);
     methodGuards = harden({
       ...mg,
       ...(symbolMethodGuards &&
         fromEntries(getCopyMapEntries(symbolMethodGuards))),
     });
+    defaultGuards = dg;
     {
       const methodNames = ownKeys(behaviorMethods);
       assert(methodGuards);
@@ -333,7 +436,6 @@ export const defendPrototype = (
       interfaceGuard,
     );
   }
-
   for (const prop of ownKeys(behaviorMethods)) {
     prototype[prop] = bindMethod(
       `In ${q(prop)} method of (${tag})`,
@@ -342,6 +444,7 @@ export const defendPrototype = (
       thisfulMethods,
       // TODO some tool does not yet understand the `?.[` syntax
       methodGuards && methodGuards[prop],
+      defaultGuards,
     );
   }
 
diff --git a/packages/exo/test/test-heap-classes.js b/packages/exo/test/test-heap-classes.js
index 8f5e753a92..c81f650357 100644
--- a/packages/exo/test/test-heap-classes.js
+++ b/packages/exo/test/test-heap-classes.js
@@ -203,6 +203,23 @@ test('sloppy option', t => {
   );
 });
 
+const RawGreeterI = M.interface('greeter', {}, { defaultGuards: 'raw' });
+
+test('raw defaultGuards', t => {
+  const greeter = makeExo('greeter', RawGreeterI, {
+    sayHello(mutable) {
+      mutable.x = 3;
+      return 'hello';
+    },
+  });
+  const mutable = {};
+  t.is(greeter.sayHello(mutable), 'hello');
+  t.deepEqual(mutable, { x: 3 });
+  mutable.y = 4;
+  t.deepEqual(mutable, { x: 3, y: 4 });
+  t.deepEqual(greeter[GET_INTERFACE_GUARD](), RawGreeterI);
+});
+
 const GreeterI = M.interface('greeter', {
   sayHello: M.call().returns('hello'),
 });
diff --git a/packages/patterns/src/types.js b/packages/patterns/src/types.js
index 298be27029..2f875de735 100644
--- a/packages/patterns/src/types.js
+++ b/packages/patterns/src/types.js
@@ -531,7 +531,8 @@ export {};
  *     Omit<T, symbol> & Partial<{ [K in Extract<keyof T, symbol>]: never }>,
  *   symbolMethodGuards?:
  *     CopyMap<Extract<keyof T, symbol>, T[Extract<keyof T, symbol>]>,
- *   defaultGuards: DefaultGuardType,
+ *   defaultGuards?: DefaultGuardType,
+ *   sloppy?: boolean,
  * }} InterfaceGuardPayload
  */