The ACSO serves as a local arm of the Pennsylvania Unified Judicial System in a number of roles, including: court security, writ services, sales, prisoner transportation, issuing of firearm licenses and execution of warrants.

[3] The Sheriff's Office also assists local law enforcement agencies with emergency and incident response on an as-needed basis, most notably through the use of trained police dogs.

[12] The first sheriff to be elected in Allegheny County was James Morrison, who took office in January 1789, soon after the United States gained independence from Great Britain in the Revolutionary War.

She was alleged to have disclosed sensitive law enforcement information to two "personal associates" who were targets of a federal investigation into a large-scale, drug trafficking organization.

[15][16] In May 2018, Deputy Donald Modrick was charged with theft, unsworn falsification and obstructing the administration of law after stealing $10,000 from a defendant.