When creating a filter, I was unable to add additional methods to the filter class without getting the additional method reported as a problem. Test case is as follows: 1. Setup a filters class as follows: class SecurityFilters { def filters = { loginCheck(controller:'', action:'') { before = { Date now = getNow() println "${now} before() called" } } } def getNow() { println "Into getNow()" return new Date() } } 2. Run grails run-app. You'll probably need to add some dummy controller to your project to trigger the filter. 3. Note in the output logging the following lines: [18078] filters.FilterConfig Setting getNow is invalid for filter config getNow Into getNow() Fri Nov 09 14:48:55 CAT 2007 before() called So even though getNow() is actually called, it seems, Grails is not altogether happy with the setup of the Filters class.