One of the purposes of such checks is to prevent any threat to the internal security and public policy of the Member States, irrespective of the origin of such threat, including where such a threat derives from Union citizens.
Ceann de na cuspóirí atá le seiceálacha den sórt sin is ea cosc a chur le haon bhagairt do shlándáil inmheánach agus do bheartas poiblí na mBallstát, beag beann ar bhunús na bagairte sin, lena n-áirítear i gcás ina dtagann an bhagairt sin ó shaoránaigh de chuid an Aontais.