what is the courthouse frequencies and mos?
Who's courthouses are you referring to? City, state or federal?
The City doesn't, technically, have courts - they are administrative tribunals, a sample of which can be found here:
http://www.nyc.gov/html/oath/html/home/home.shtml To my knowledge security is provided by contract security officers
If you're referring to the State courts (Criminal, Supreme, Housing, Civil, and Family), Court Officers from the Unified Court System provide law enforcement / security services. You can pick off the frequencies for them by looking in the ULS database for the following FCC call signs:
Manhattan
WPWK586
WPZR749
WPZR751
WQUI559
WQQZ563
Bronx
WQNL226
KNDK573
WQUI559
Brooklyn
WQQZ563
WQUI559
Queens
WPNS287
WQUI559
Staten Island
WQUI559
WPUW554
UCS Mobile Security units have access to the Metro21 trunked system as well (talkgroup 6041).
"Traffic" Court is actually the Administrative Adjudication Bureau of the state's Department of Motor Vehicles. Security is typically provided by the building the "Court" is housed in (and, by default, all the cops coming and going for hearings).
Federal courts are protected by special deputy United States Marshals (internal posts and external posts), private security contractors (external posts), and Deputy US Marshals (anywhere they need to be).