- Keeping the peace across the entire planet
- Issuing permits
- Arresting and jailing outlaws
- Enforcing public code
- Diplomatic relations with native citizens and offworld aliens, as well as the USSA
- Paperwork. Lots and lots of paperwork.
The job of Marshal on Mars has been held by three men and one robot:
- Pemily Stallwark has been recommended by Sparks Nevada for the job of Marshal on the Earth's Moon after the events of Moonfaker.
Known deputies to marshals on Mars are:
- Rusty, an android, was Simon Pure's deputy
- Cactoid Jim very briefly (for about five minutes) served as Sparks Nevada's deputy. He has also been temporarily deputized on occasion so Sparks Nevada could have a day off.
- The Red Plains Rider was also unofficially Sparks Nevada's deputy for a short time on a work-release program to clear the bounty on her head for killing Erica Peeples before she was completely MurderManned. She, too, has been temporarily deputized on other occasions to assist Sparks Nevada.
- Croach the Tracker has never officially been Sparks Nevada's deputy, but is occasionally referred to as such for brevity's sake. He performs all the deputy duties without pay or title, as holding human office would bring shame upon him and would risk exile from his tribe. He did accept the position as The Red Plains Rider's deputy, however.
- Pemily Stallwark was sent by Gene Peeples to deputy for Sparks Nevada after she did not complete USSA Academy.