After obtaining a Master's degree in Private Law from the University of Metz, and a post-graduate diploma in Business Administration from the Ecole Supérieure de Management in Metz, then a degree in Criminology from the University of Nancy, David Oniarci was called to the Bar of Luxembourg in 2009.

He has been a solicitor since 2012 and his specialties are Administrative law and Public Contracting, Construction law, Real Estate law, Transportation law, Criminal Traffic law, Liability law and Compensation for Bodily Injury.

He speaks French, German and Polish.