He obtained his doctorate in law, passed his Referendar examination and began a legal clerkship at the higher regional court in Hamm in 1902.

He performed mandatory military service with the Royal Prussian Army as a one-year volunteer from October 1902 with the 7th (Rhenish) Uhlan Regiment, based in Sankt Johann (Saarbrücken).

Franz Bracht, the Oberbürgermeister of Essen, was named Prussian Commissioner for the Interior and he installed Melcher as Police President of Berlin, succeeding the Social Democrat Albert Grzesinski.

However, on 29 September 1933, he was replaced as Oberpräsident by Curt von Ulrich but retained his seat on the State Council until the fall of the Nazi regime in 1945.

[1] In 1937, he also functioned as the transition commissioner for the incorporation of the Free City of Lübeck into the state of Prussia under the provisions of the Greater Hamburg Act.