[1] In 1960, Arlington County Police arrested people for violating Virginia's segregation and anti-miscegenation laws.

[5] In June 2020, Arlington County withdrew its personnel from the District of Columbia after Arlington County Police Department officers were involved in an incident in which protesters were forcefully cleared from Lafayette Park.

[6][7][8] An Arlington County Police Department captain was later named in a federal lawsuit related to the incident.

On June 4, 2021, Penn was appointed to be the permanent Chief of Police by Arlington County Manager Mark Schwartz.

[12][13] Since the establishment of the Arlington County Police Department, 7 officers have died in the line of duty,[14] the most recent in 2016 as a result of an illness caused by the September 11 attacks of 2001.