In 1919, Germany adopted the Weimar Constitution. After its loss in the First World War and the abdication of the Kaiser, Germany formally became a liberal democracy and a parliamentary democracy.
Article 48 of the Weimar Constitution allowed for what Italian philosopher Giorgio Agamben calls “a state of exception.” In an emergency, the article allowed the German president to unilaterally direct the military to do whatever he felt necessary to restore order, including the indefinite suspension of fundamental rights articulated elsewhere in the constitution.
In 1933, Hitler—having been appointed as chancellor despite not having won an election—persuaded President Paul von Hindenburg to issue a decree, per Article 48 of the constitution, suspending most constitutional rights.
This was the first of *many perfectly legal steps* that Hitler undertook to transform Germany into a totalitarian state.