ARC Legal Assistance said it now covers 24,000 police officers throughout five English police forces after signing a contract with the Metropolitan Police Federation.
Under the deal, officers will have cover for criminal prosecution relating to events occurring while they are off duty, designed specifically to aid officers who are the victims of vindictive crimes, said ARC director Frank O'Malley.
The Met already provides cover for events occurring while officers are on duty.
ARC said one in five police officers in England and Wales now has legal assistance cover through the company.
The policy was developed in partnership with underwriter Allianz Cornhill Legal Protection and the broker is George Burrows.