1.Where, in the area without internal border control, there is a serious threat to public policy or internal security in a Member State, that Member State may exceptionally reintroduce border control at all or specific parts of its internal borders for a limited period of up to 30 days or for the foreseeable duration of the serious threat if its duration exceeds 30 days. The scope and duration of the temporary reintroduction of border control at internal borders shall not exceed what is strictly necessary to respond to the serious threat.
2.Border control at internal borders shall only be reintroduced as a last resort, and in accordance with Articles 27, 28 and 29. The criteria referred to, respectively, in Articles 26 and 30 shall be taken into account in each case where a decision on the reintroduction of border control at internal borders is considered pursuant, respectively, to Article 27, 28 or 29.
3.If the serious threat to public policy or internal security in the Member State concerned persists beyond the period provided for in paragraph 1 of this Article, that Member State may prolong border control at its internal borders, taking account of the criteria referred to in Article 26 and in accordance with Article 27, on the same grounds as those referred to in paragraph 1 of this Article and, taking into account any new elements, for renewable periods of up to 30 days.
4.The total period during which border control is reintroduced at internal borders, including any prolongation provided for under paragraph 3 of this Article, shall not exceed six months. Where there are exceptional circumstances as referred to in Article 29, that total period may be extended to a maximum length of two years, in accordance with paragraph 1 of that Article.