diff --git a/src/access-controllers/index.js b/src/access-controllers/index.js
index ec850de..9fb39a0 100644
--- a/src/access-controllers/index.js
+++ b/src/access-controllers/index.js
@@ -1,21 +1,30 @@
 /**
  * @module AccessControllers
  * @description
- * Provides a platform for managing access controllers. Supported access
+ * Provides a system for managing access controllers. Supported access
  * controllers can be added and removed from the access controller list, and
  * can load the associated module if they are supported.
  *
- * An AccessController module needs to only expose one function,
- * canAppend(entry) which returns true if the entry can be appended to the
- * oplog, or false otherwise:
- * ```javascript
- * const CustomAccessController = ({ write } = {}) => async => {
+ * An AccessController module needs to only expose one constant, type, and one function, canAppend(entry), which returns true if the entry can be appended to
+ * the oplog, or false otherwise:
+ * ```js
+ * type = 'custom'
+ *
+ * const CustomAccessController = ({ write } = {}) => async ({ orbitdb, identities, address }) => {
  *   const canAppend = async (entry) => {
  *     // Use entry.identity to determine whether the entry can be appended.
  *     // Return true if entry can be appended to OpLog.
  *     // Or return false otherwise.
  *   }
+ *
+ *   return {
+ *     canAppend,
+ *     type
+ *   }
  * }
+ *
+ * export default CustomAccessController
+ * ```
  */
 import IPFSAccessController from './ipfs.js'
 import OrbitDBAccessController from './orbitdb.js'
@@ -37,7 +46,7 @@ const accessControllers = {
  * @return {AccessController} The access controller module.
  */
 const getAccessController = (type) => {
-  if (!Object.keys(accessControllers).includes(type)) {
+  if (!accessControllers[type]) {
     throw new Error(`AccessController type '${type}' is not supported`)
   }
   return accessControllers[type]
@@ -53,12 +62,12 @@ const getAccessController = (type) => {
  * controller module does not implement a type property.
  */
 const addAccessController = (accessController) => {
-  if (accessControllers[accessController.type]) {
-    throw new Error(`Access controller '${accessController.type}' already added.`)
+  if (!accessController.type) {
+    throw new Error('Access controller does not contain required field \'type\'')
   }
 
-  if (!accessController.type) {
-    throw new Error('Given AccessController class needs to implement: type.')
+  if (accessControllers[accessController.type]) {
+    throw new Error(`Access controller '${accessController.type}' already added.`)
   }
 
   accessControllers[accessController.type] = accessController