diff --git a/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehicleAreaConfig.aidl b/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehicleAreaConfig.aidl
index 726d419..9387965 100644
--- a/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehicleAreaConfig.aidl
+++ b/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehicleAreaConfig.aidl
@@ -62,7 +62,9 @@
      * For example, if a property is defined as READ_WRITE, but the OEM wants to specify certain
      * area Ids as READ-only, the corresponding areaIds should have an access set to READ, while the
      * others must be set to READ_WRITE. We do not support setting specific area Ids to WRITE-only
-     * when the property is READ-WRITE.
+     * when the property is READ-WRITE. If any one area config has access
+     * VehiclePropertyAccess::WRITE, then all VehicleAreaConfig.access values and
+     * VehiclePropConfig.access must be set to WRITE for the property.
      *
      * VehiclePropConfig.access should be equal the maximal subset of the accesses set in
      * VehiclePropConfig.areaConfigs, excluding those with access == VehiclePropertyAccess.NONE. For
@@ -73,6 +75,8 @@
      * In the scenario where the OEM actually wants to set VehicleAreaConfig.access =
      * VehiclePropertyAccess.NONE, the maximal subset rule should apply with this area config
      * included, making the VehiclePropConfig.access = VehiclePropertyAccess.NONE.
+     *
+     * See VehiclePropConfig.access for more information.
      */
     VehiclePropertyAccess access = VehiclePropertyAccess.NONE;
 
diff --git a/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehiclePropConfig.aidl b/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehiclePropConfig.aidl
index 3109621..d8304f6 100644
--- a/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehiclePropConfig.aidl
+++ b/automotive/vehicle/aidl/android/hardware/automotive/vehicle/VehiclePropConfig.aidl
@@ -44,6 +44,36 @@
      * VehiclePropertyAccess.NONE for a particular area config, the maximal subset rule should apply
      * with this area config included, making the VehiclePropConfig.access =
      * VehiclePropertyAccess.NONE.
+     *
+     * Currently we do not support scenarios where some areaIds are WRITE while others are
+     * READ_WRITE. See the documentation for VehicleAreaConfig.access for more details.
+     *
+     * Examples:
+     *   Suppose we have a property with two areaIds which we will call "LEFT" and "RIGHT". Here
+     *   are some scenarios that can describe what the VehiclePropConfig.access value should be for
+     *   this property.
+     *   1. LEFT is READ and RIGHT is READ_WRITE. VehiclePropConfig.access must be READ as that is
+     *      the maximal common access across all areaIds.
+     *   2. LEFT is READ_WRITE and RIGHT is READ_WRITE. VehiclePropConfig.access must be READ_WRITE
+     *      as that is the maximal common access across all areaIds.
+     *   3. LEFT is WRITE and RIGHT is WRITE. VehiclePropConfig.access must be WRITE as that is the
+     *      maximal common access across all areaIds.
+     *   4. LEFT is READ_WRITE and RIGHT is not set (i.e. defaults to NONE)/is set to NONE, with the
+     *      expectation that RIGHT should be populated with the default access mode of the property.
+     *      VehiclePropConfig.access can be set to READ or READ_WRITE, whatever the OEM feels is the
+     *      appropriate default access for the property.
+     *   5. LEFT is READ and RIGHT is not set (i.e. defaults to NONE)/is set to NONE, with the
+     *      expectation that RIGHT should be populated with the default access mode of the property.
+     *      VehiclePropConfig.access must be set to READ because setting to READ_WRITE breaks the
+     *      rule of having the global access being the maximal subset of the area config accesses.
+     *      If the OEM wants RIGHT to be READ_WRITE in this scenario, the config should be rewritten
+     *      such that LEFT is not set/is set to NONE and RIGHT is set to READ_WRITE with
+     *      VehiclePropConfig.access set to READ.
+     *   6. LEFT is READ_WRITE and RIGHT is set to NONE with the intention of RIGHT to specifically
+     *      have no access. VehiclePropConfig.access must be NONE to support RIGHT maintaining its
+     *      NONE access.
+     *   7. LEFT is READ_WRITE and RIGHT is WRITE. This is unsupported behaviour and the config
+     *      should not be defined this way.
      */
     VehiclePropertyAccess access = VehiclePropertyAccess.NONE;
 
diff --git a/automotive/vehicle/vts/src/VtsHalAutomotiveVehicle_TargetTest.cpp b/automotive/vehicle/vts/src/VtsHalAutomotiveVehicle_TargetTest.cpp
index 4ea6dfe..30661a2 100644
--- a/automotive/vehicle/vts/src/VtsHalAutomotiveVehicle_TargetTest.cpp
+++ b/automotive/vehicle/vts/src/VtsHalAutomotiveVehicle_TargetTest.cpp
@@ -752,9 +752,15 @@
         }
     }
 
-    if (readOnlyPresent && !writeOnlyPresent) {
+    if (readOnlyPresent) {
+        ASSERT_FALSE(writeOnlyPresent) << StringPrintf(
+                "Found both READ_ONLY and WRITE_ONLY access modes in area configs, which is not "
+                "supported");
         maximalAreaAccessSubset = toInt(VehiclePropertyAccess::READ);
     } else if (writeOnlyPresent) {
+        ASSERT_FALSE(readWritePresent) << StringPrintf(
+                "Found both WRITE_ONLY and READ_WRITE access modes in area configs, which is not "
+                "supported");
         maximalAreaAccessSubset = toInt(VehiclePropertyAccess::WRITE);
     } else if (readWritePresent) {
         maximalAreaAccessSubset = toInt(VehiclePropertyAccess::READ_WRITE);