The part of the Weimar constitution that allowed the President to take emergency powers without consulting the Reichstag

article 48 section 5

Article 48 of the Weimar constitution allowed the president to rule by decree at times of an emergency and gave the president the right to override the Reichstag and provide leadership "above party".
Article 48 of the Weimar constitution made provision for rule by decree in an emergency.

He could pass any laws without verification from the Reichstag - if he deemed it an emergency. Inevitably, Hitler abused this power and took absolute control.