Following a Master's degree from the University of Nancy, James Junker became a member of the Bar of Luxembourg in 1986. He has been a solicitor since 1988 and has assisted and represented clients as such in all jurisdictions in the Grand Duchy of Luxembourg for over 30 years.

He is a constant attendee at conferences. He is legal counsel to the European institutions. He is Chairman of the Luxembourg Olympic and Sports Advisory Council. 

His legal specialties include Corporate law, Labour law, Contract law, Administrative law, Tax law, Real Estate law, Economic and Financial Criminal law and Business law.

He is author of "Sécurité et Santé en droit du travail luxembourgeois" (Health and Safety in Luxembourg Labour Law), (Editions Bauler, ISDN n° 978-291988507) and of a study entitled "La facture en droit luxembourgeois" (Invoicing in Luxembourg law)(Bulletin du Cercle François Laurent, n° 2002/I-IV).

He speaks German, English, French and Luxembourgish.