In exceptional circumstances where the overall functioning of the area without internal border control is put at risk as a result of persistent serious deficiencies relating to external border control as referred to in Article 21, and insofar as those circumstances constitute a serious threat to public policy or internal security within the area without internal border control or within parts thereof, border control at internal borders may be reintroduced in accordance with paragraph 2 of this Article for a period of up to six months.
I gcúinsí eisceachtúla ina gcuirtear feidhmiú foriomlán an limistéir gan rialú ag teorainneacha inmheánacha i mbaol mar thoradh ar easnaimh thromchúiseacha leanúnacha a bhaineann le rialú ag teorainn sheachtrach dá dtagraítear in Airteagal 21, agus a mhéid is gur baol tromchúiseach iad na cúinsí sin do bheartas poiblí nó do shlándáil inmheánach laistigh den limistéar gan rialú ag teorainneacha inmheánacha nó i gcodanna de, féadfar rialú teorann ag teorainneacha inmheánacha a athbhunú i gcomhréir le mír 2 den Airteagal seo ar feadh tréimhse sé mhí ar a mhéid.