Jonathan was called to the Bar in 1991 and practised at 30 Park Place, Cardiff until May 2008 when he joined 1 Stanley Place Chambers. He is a senior criminal practitioner with extensive experience of serious sexual abuse and murder cases. He has prosecuted many high-value fraud matters for HM Revenue & Customs, including multi-million duty evasion cases and carousel VAT frauds. He also appears regularly for other government agencies such as:

· DEFRA
· DTI
· The Environment Agency
· The Health & Safety Executive
· Countryside Council for Wales

Jonathan regularly conducts cases for local authorities around Wales in animal welfare and food safety matters and presents cases for the RSPCA.

Jonathan originates from North Wales having been born and brought up in Anglesey. He is a fluent Welsh speaker and an enthusiastic user of the language in Court. He initially took a BA degree in French followed by a postgraduate LLB at Aberystwyth. In 1989, Jonathan also studied Government at the Catholic University in Washington DC whilst serving as a Congressional intern in the US House of Representatives.

Jonathan has served on the Welsh Books Council, on the governing body of the National Museum of Wales, and Cardiff MIND.