Internal Security (or InSec for short) was part of the bureaucracy of the Earth Federation. It was initially started as a customs enforcement wing in 2148, when Earth Fleet was stretched thin over the Fed's colonized space and needed to focus on fighting the Drakat. Its powers soon expanded to fight pirates and later minor rebellions deemed unimportant for the regular military to handle.
It added intelligence gathering to its role after the 1st Civil War, when it was feared that the Grand Council needed to be checked in order to preserve their democracy. Unfortunately, that role was usurped by the Technocracy, who used it as their military arm in order to conduct black ops throughout the Federation.
InSec reached its height under the administration of Colonel Rashid King. After Dunmeyer's failed coup, Internal Security gained more and more power within the Grand Council Loyalists. When this power became a danger to Chairman Abdul Johnson, he tried to reign in his friend, only to have King lead a coup to place himself in power. The coup succeeded, but Rashid was killed by Xavier Pollos afterwards, leaving a power vacuum that was filled by Arthur Clarke.
After Clarke's takeover, Internal Security was officially disbanded, although many of its operatives and assets went underground. Many of InSec's former functions were taken up by the Raptors.