The Omnibus Consolidated Appropriations Act of 1997 amended the Federal Gun Control Act of 1968. Basically, an officer who has been convicted of a "qualifying misdemeanor" crime of domestic violence cannot possess any weapon, even his service firearm, at any time. Reference: 18 USC 922 (g)(9)
The Lautenberg Amendment to the Gun Control Act was enacted September 30, 1996, however the law is retroactive. This means that an officer who has ever been convicted of a qualifying misdemeanor of domestic violence is prohibited from possessing a weapon, unless his record has been expunged.
The Violence Against Women Act of 1994 states that a person subject to a qualifying Order of Protection is not allowed to possess a personal firearm or personal ammunition. This restriction does not apply to law enforcement service weapons. Police officers are allowed to carry their official-use firearm unless the Order specifically states that s/he cannot possess a firearm at any time. Reference: 18 USC 922 (g)(8)
An Order of Protection does not prohibit the officer from carrying a service weapon unless the order specifically states that s/he is not to possess any weapon at any time. This remedy is only granted in the most extreme cases. The judge must be convinced that there is a high risk that the abuser would use the service weapon against you.
Some police departments have a policy that prohibits an officer who is subject to a protective order from carrying a firearm even while on duty. Other departments may allow the officer to carry a firearm on duty, but require that the weapon is turned in at the end of the shift. In most departments, police officers who are subject to protective orders are allowed to carry their firearms and remain on full active duty, but every department has the authority to strip an officer of his police powers.
In reality, few officers are convicted of domestic violence misdemeanors. Prosecutors generally allow officers to plead guilty to a lesser charge, one that does not trigger the gun restriction. For example, a reduced charge might be reckless conduct, simple assault or simple battery, or disturbing the peace.
Departments are not mandated to fire an officer with a conviction. The officer can be reassigned to an administrative position that does not require carrying a firearm. The department's decision on whether to retain an officer depends on many factors, including the size of the department and the abuser's professional reputation.