Concord Security is a multi-species police force first formed shortly after the dedication of the Citadel as the home of Concord politics. At first, they saw to the security of the Council, senators, and various ambassadors and their retinues arriving on the Citadel to do business. After the formation of the Concord Navy, the direct protection of the Council and Senate fell to the Concord Marines. C-Sec was then tasked with policing the rest of the Citadel, the docking stations, warehouses, commercial and residential zones. As the influence of the Concord grew, so did the number of culture-neutral space stations, supply colonies, and various other non-military installations. (Referring to an area as "culture-neutral" means that no one stellar nation is dominant on that installation.) C-Sec was expanded to keep the peace and uphold the law in these areas as well.
In order to have laws to uphold, before C-Sec was founded, and not long after the signing of the Galactic Concord Constitution, a set of standard laws was passed that apply to any cultural-neutral area under Concord control. These are the usual laws against murder, theft, violence, trafficking in contraband, etc. These sets of laws still cause the occasional diplomatic flap as not all cultures see all of these Standard Laws as criminal offences and some cultures don't think there are enough offenses. Lawbreakers are taken before Concord Courts where sentencing is meted out by the standard set in the Standard Laws Code. Again, the length and type of punishment is always agreeable to every society.
C-Sec is organized similar to Earth police precincts. The head of C-Sec, the Attorney General, answers to the Council. Each sector is then governed by a Commissioner that answers to the AG. Each precinct is under the command of a Captain. Sergeants rank below Captains and are in charge during times that the Captain is off-duty. Detectives are next in the chain of command and are tasked primarily with the investigations of crimes. Officers are the lowest rank of C-Sec and are the standard "beat cop" of the precinct. The number of detectives and officers will vary from precinct to precinct based on the need. Some precincts in areas with high crime rates or high rates of certain types of crimes may have special investigation units that are better trained to handle those certain types of crimes (Narcotics, Slavers, Sex Crimes, etc.).
In addition to protection and investigation, most precincts in high population areas will also have special units trained to deal with high danger situations like terrorism or hostage situations. These Special Weapons and Tactics (SWAT) units tend are better trained and equipped than standard officers. In some precincts officers may serve double duty as officers and in SWAT units, but that is usually rare.
C-Sec also has a self-policing division called Internal Affairs. This division is highly unpopular as they "police the police." IA investigates and looks for evidence of wrong-doing by C-Sec officials from the AG down to the officers. This division is headed up by the Director of Internal Affairs, who answers to the AG, but in cases involving graft by the AG or his personal staff, the Director then answers to the Council itself. IA consists primarily of agents trained in a variety of disciplines ranging from espionage to accounting. When necessary, they can call upon detectives and officers in a precinct to aid in their investigations.
The third and final division of C-Sec is the Special Investigations Bureau. SIB primarily concerns itself with large threats usually uncovered by precincts like large slave rings and organized crime. SIB also has the authority to investigate crimes of sensitive nature in the Concord Navy (most common crimes are handled by the Navy's own Military Police division). SIB has the authority to take over investigations currently being handled by individual precincts when directed to do so by the AG. SIB agents are typically trained in a variety of areas and are usually very experienced in law enforcement.