Growing up in Dublin, Justin played regularly with many jazz musicians such as Louis Stewart, Richie Buckley, John Wadham, Michael Buckley, Ronan and Conor Guilfoyle. Justin was a member of jazz quintet 'Metier' led by Ronan Guilfoyle. They were artists in residence with Dun Laoghaire/ Rathdown County Council for three years and in that time performed with guest artists Vincent Courtois and Nils Wogram. They also performed at the London Jazz Festival and European Nights Festival in Oslo, Norway.
Justin has worked with many touring jazz musicians such as Greg Osby, Bobby Watson, Ronnie Cuber, Loren Stillman, Jason Rigby, Ed Rosenberg, Nils Wogram, Stéphane Payen, Tom Arthurs, as well as leading Dublin based quartet 'Togetherness' and playing with an organ trio 'Organics' who started as a regular Friday night fixture at Slattery's bar in Rathmines, Dublin and went on to perform extensively in Ireland, Mexico, USA and South Africa.