I got solution!!!! Followed Toni Rikolla http://stackoverflow.com/questions/13572661/drools-guvnor-how-do-dates-an... rule "name" when DateRange($endDate: endDate !=null, isValidStructure($endDate.toString)); then log.info("..........") end function Boolean isValidStructure (String date){ } From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Gopu Shrestha Sent: Thursday, March 13, 2014 10:54 AM To: Rules Users List Subject: [rules-users] compare date structure in WHEN part I want to compare the date structure YYYY-MM-DD in when part. Can I do this?? any help will be appreciated.. rule "name" when DateRange($endDate: endDate !=null) // $endDate ==" YYYY-MM-DD" structure then log.info("..........") end