Where control of the external borders is rendered ineffective to such an extent that it risks jeopardising the functioning of the Schengen area because:
I gcás ina bhfágtar go bhfuil rialú ag na teorainneacha seachtracha chomh neamhéifeachtach sin go bhféadfaí feidhmiú limistéar Schengen a chur i mbaol ós rud é: