The Inter-Solar System Police (ISSP) is the police force across all inhabited planets and moons in the Solar System.
The chief of police in Mars is Hoffman.
The ISSP sometimes conducted experiments on people. In 2071, they conducted what they called an "assassination skills enhancement" experiment during which a person was physically and genetically enhanced. The experiment was cancelled and one of its subjects, Mad Pierrot, was kept in isolation. He escaped and took revenge on high-level ISSP directors until killed by Spike Spiegel.
- Earth Police Department
- Mars Police Department
- Tijuana Police Deparmtent
- Ganymede Police Department
- Venus Police Department
- Io Police Department
In keeping with the noir tone of the series, the ISSP is corrupt and engages in illegal activity (such as the creation of Mad Pierrot). Due to its inept officers, it often puts bounties on the heads of wanted criminals that are able to escape the law. However, as seen in Knockin' on Heaven's Door, the ISSP is capable of serious activity if warranted.