diff --git a/core/lib/Drupal/Core/Access/AccessCheckInterface.php b/core/lib/Drupal/Core/Access/AccessCheckInterface.php
index 0280330..9622295 100644
--- a/core/lib/Drupal/Core/Access/AccessCheckInterface.php
+++ b/core/lib/Drupal/Core/Access/AccessCheckInterface.php
@@ -16,6 +16,21 @@
 interface AccessCheckInterface {
 
   /**
+   * @TODO
+   */
+  const ACCEPT = TRUE;
+
+  /**
+   * @TODO
+   */
+  const KILL = FALSE;
+
+  /**
+   * @TODO
+   */
+  const DENY = NULL;
+
+  /**
    * Declares whether the access check applies to a specific route or not.
    *
    * @param \Symfony\Component\Routing\Route $route
diff --git a/core/lib/Drupal/Core/Access/AccessManager.php b/core/lib/Drupal/Core/Access/AccessManager.php
index 879ddb9..8743664 100644
--- a/core/lib/Drupal/Core/Access/AccessManager.php
+++ b/core/lib/Drupal/Core/Access/AccessManager.php
@@ -135,11 +135,11 @@ protected function checkAnd(array $checks, Route $route, Request $request) {
       }
 
       $service_access = $this->checks[$service_id]->access($route, $request);
-      if ($service_access === FALSE) {
+      if ($service_access === AccessCheckInterface::KILL) {
         $access = FALSE;
         break;
       }
-      if ($service_access === TRUE) {
+      if ($service_access === AccessCheckInterface::ACCEPT) {
         $access = TRUE;
       }
     }
@@ -170,12 +170,11 @@ protected function checkOr(array $checks, $route, $request) {
       }
 
       $service_access = $this->checks[$service_id]->access($route, $request);
-      if ($service_access === TRUE) {
+      if ($service_access === AccessCheckinterface::ACCEPT) {
         return TRUE;
       }
-      if ($service_access === FALSE) {
-        $access = FALSE;
-        break;
+      if ($service_access === AccessCheckInterface::KILL) {
+        return FALSE;
       }
     }
 
diff --git a/core/lib/Drupal/Core/Access/DefaultAccessCheck.php b/core/lib/Drupal/Core/Access/DefaultAccessCheck.php
index 224e206..20f2f16 100644
--- a/core/lib/Drupal/Core/Access/DefaultAccessCheck.php
+++ b/core/lib/Drupal/Core/Access/DefaultAccessCheck.php
@@ -23,17 +23,18 @@ public function applies(Route $route) {
   }
 
   /**
-   * Implements AccessCheckInterface::access().
+   * {@inheritdoc}
    */
   public function access(Route $route, Request $request) {
     if ($route->getRequirement('_access') === 'TRUE') {
-      return TRUE;
+      return static::ACCEPT;
     }
     elseif ($route->getRequirement('_access') === 'FALSE') {
-      return FALSE;
+      return static::KILL;
     }
     else {
-      return NULL;
+      return static::DENY;
     }
   }
+
 }
diff --git a/core/modules/user/lib/Drupal/user/Access/PermissionAccessCheck.php b/core/modules/user/lib/Drupal/user/Access/PermissionAccessCheck.php
index 9318189..2b3fc59 100644
--- a/core/modules/user/lib/Drupal/user/Access/PermissionAccessCheck.php
+++ b/core/modules/user/lib/Drupal/user/Access/PermissionAccessCheck.php
@@ -31,6 +31,6 @@ public function access(Route $route, Request $request) {
     // @todo Replace user_access() with a correctly injected and session-using
     //   alternative.
     // If user_access() fails, return NULL to give other checks a chance.
-    return user_access($permission) ? TRUE : NULL;
+    return user_access($permission) ? static::ACCEPT : static::DENY;
   }
 }
diff --git a/core/modules/user/lib/Drupal/user/Access/RoleAccessCheck.php b/core/modules/user/lib/Drupal/user/Access/RoleAccessCheck.php
index 104763d..9e50de7 100644
--- a/core/modules/user/lib/Drupal/user/Access/RoleAccessCheck.php
+++ b/core/modules/user/lib/Drupal/user/Access/RoleAccessCheck.php
@@ -42,19 +42,19 @@ public function access(Route $route, Request $request) {
     if (count($explode_and) > 1) {
       $diff = array_diff($explode_and, array_keys($account->roles));
       if (empty($diff)) {
-        return TRUE;
+        return static::ACCEPT;
       }
     }
     else {
       $explode_or = array_filter(array_map('trim', explode(',', $rid_string)));
       $intersection = array_intersect($explode_or, array_keys($account->roles));
       if (!empty($intersection)) {
-        return TRUE;
+        return static::ACCEPT;
       }
     }
 
-    // If there is no allowed role, return NULL to give other checks a chance.
-    return NULL;
+    // If there is no allowed role, return DENY to give other checks a chance.
+    return static::DENY;
   }
 
 }