At a time when Superman was suspected of being an impostor after his body was found to be still in his tomb, Carl Draper was hired by S.T.A.R. Labs to design a holding cell for the super villain Conduit, when his daughter, Carla, asked him if he could build a prison that could hold Superman. Draper initially designed a trap that only the real Superman could escape from, explaining this to Superman by way of a hologram of a costumed figure named Deathtrap. However, when Superman escaped the trap, Draper became obsessed with proving he could capture the real thing.
Master Jailer has no super human powers, however he is a highly skilled engineer and strategist. He is also a master at building traps.
(note: he is also quite similar to the Batman rogue known as Lockup - though this could purely be coincidence).