diff --git a/src/Xacmlphp/Decider.php b/src/Xacmlphp/Decider.php
index 952c4f1..6928455 100644
--- a/src/Xacmlphp/Decider.php
+++ b/src/Xacmlphp/Decider.php
@@ -52,7 +52,7 @@ public function getSubjectAttributes()
      *
      * @return bool
      */
-    public function evaluate(Subject $subject, PolicySet $policySet, Action $action)
+    public function evaluate(Subject $subject, PolicySet $policySet, Action $action = null)
     {
         // get the subject's attributes
         $this->setSubjectAttributes($subject->getAttributes());
@@ -147,4 +147,4 @@ public function handleMatches(array $matches)
         }
         return $results;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Xacmlphp/Enforcer.php b/src/Xacmlphp/Enforcer.php
index 6988e72..1d2e1e6 100644
--- a/src/Xacmlphp/Enforcer.php
+++ b/src/Xacmlphp/Enforcer.php
@@ -60,7 +60,7 @@ public function getDecider()
      *
      * @return bool Allowed/not allowed status
      */
-    public function isAuthorized(Subject $subject, Resource $resource, Action $action)
+    public function isAuthorized(Subject $subject, Resource $resource, Action $action = null)
     {
         $decider = $this->getDecider();
         if ($decider === null) {
@@ -71,4 +71,4 @@ public function isAuthorized(Subject $subject, Resource $resource, Action $actio
 
         return $decider->evaluate($subject, $policies, $action);
     }
-}
\ No newline at end of file
+}