One of the famous Ace Doubles, with the wonderful original cover, One Against Herculum remains a fast-paced, fun story that you'll really enjoy.
LEGAL ASSASSIN OF THE STARWAYS
Corruption was the rule of order on the domed planetary colony of Herculum. Earthman Alan Demuth, for instance, couldn't get the job he had rightfully qualified for without paying a kickback to the man he hated, Jack Bohannen. Alan thought he could simply report Jack's graft, until he learned none would listen.
There was one desperate recourse. Under provision of the law, Alan could ask for a crime license. His crime would be homicide, and the victim Jack Bohannen. The law gave him twenty-four hours to make good his murder.
Failure would mean Alan's death. Success would mean the clean-up of graft and dishonesty. But Alan never realized that in a graft-ridden society, even a license to kill is liable to prove a backfiring fraud!
Jerry Sohl is the author of over two dozen books, as well as many scripts for Star Trek, The Outer Limits, The Twilight Zone, and numerous other TV shows and feature films.