UNSC Medical Corps
From Halopedia, the Halo wiki
The UNSC Medical Corps, also shortened to UNSC MED CORPS, was a branch of HIGHCOM responsible for the medical treatmenived medical attention so they could be returned to duty. They also made policies on which drugs were legal and which were not.
In Ghosts of Onyx, they are cited by Deep Winter as the body which made brain mutagens illegal.