diff --git a/core/event.class.php b/core/event.class.php
index abc0f189..67f1bcd7 100644
--- a/core/event.class.php
+++ b/core/event.class.php
@@ -5,10 +5,17 @@
  */
 abstract class Event {
 	var $context;
+	var $vetoed = false;
+	var $veto_reason;
 
 	public function __construct(RequestContext $context) {
 		$this->context = $context;
 	}
+
+	public function veto($reason="") {
+		$this->vetoed = true;
+		$this->veto_reason = $reason;
+	}
 }
 
 
diff --git a/core/util.inc.php b/core/util.inc.php
index 7bda4061..3e262087 100644
--- a/core/util.inc.php
+++ b/core/util.inc.php
@@ -505,6 +505,7 @@ function send_event($event) {
 	ksort($my_event_listeners);
 	foreach($my_event_listeners as $listener) {
 		$listener->receive_event($event);
+		if($event->vetoed) break;
 	}
 	$_event_count++;
 }