Judicial cooperation in criminal matters in the Union is based on the principle of mutual recognition of judgments and judicial decisions, which has commonly been referred to as the cornerstone of judicial cooperation in criminal matters within the Union since the Tampere European Council of 15 and 16 October 1999.
Tá comhar breithiúnach in ábhair choiriúla san Aontas bunaithe ar phrionsabal an aitheantais fhrithpháirtigh do bhreithiúnais agus do chinntí breithiúnacha, a dtugtar an bunchloch don chomhar breithiúnach in ábhair choiriúla laistigh den Aontas air go coitianta ón tráth ar tionóladh an cruinniú den Chomhairle Eorpach in Tampere an 15 agus 16 Deireadh Fómhair 1999.