Given this rule rule "show no gaps" when not Gap() then System.out.println( "No gaps!" ); end the ActivationCreatedEvent references an Activation, where the list of fact handles (getFactHandles) contains one element, but its Object is null: Fact null @0:0:27032609:1306428912:0:DEFAULT But the list of objects (getObjects) returns a list where there *is* an object: Object (org.drools.reteoo.InitialFactImpl): org.drools.reteoo.InitialFactImpl@4dde85f0 I think that this should be changed; neither a fact handle nor an object should be returned if there are no user objects participating in the activation. Cheers Wolfgang