British, Irish and Danish legal policy derogations 

The British,Irish and Danish governments opt-in and opt-out system of justice and home affairs allows them to decide when particular policy choices arise, whether they want to participate or not. Ireland and Britain had a similar opt-in under the Treaty of Nice. 

See Lisbon Treaty Protocols 15, 19, 20, 21 and 30 for the British derogations and Protocol 35 on abortion  for a derogation for Ireland. 

See Protocol 17, 22, 32 and 34 for the Danish derogations.