In April 2007, while still working as a coach development officer for Munster Rugby, Lacey agreed to take charge of a Munster Schools Junior Cup quarter-final between St Munchin's College and CBC after the original referee failed to show up. He subsequently began refereeing games in the All-Ireland League before making his Celtic League debut on 28 November 2008 when he took charge of a game between Edinburgh and the Ospreys.