What are the authority limits for various police units regarding traffic law enforcement?
I live in the DC area which includes city, county, state, metropolitan, and various agency police forces on the highways, such as Prince George’s County, Alexandria City, Fairfax County, Arlington County, DC Metro police, US Park Police, DHS Federal Protective Police, Metro Transit Police, VA State Police, and MD State Police. Obviously some have more obvious jurisdiction limits like VA and MD state, county, and city police.
However, I see DC metropolitan, Metro Transit, DHS, and Park police in MD and VA areas. Are they allowed to enforce traffic laws? Are DC police’s jurisdiction including the entire DMV metro area or just within DC city limits? I obviously understand the importance of safe and lawful driving but am curious as to whether the general driving populace’s fear of getting pulled over when driving past, say a Transit officer.