The Starfleet base where a 2365 hearing decided whether Data was a person or Starfleet property.
Starbase 173 was a Starfleet starbase that hosted the Enterprise-D during a crew rotation in 2365. It was also the site of a newly opened office of the Judge Advocate General, headed by Captain Phillipa Louvois.
Commander Bruce Maddox arrived there intending to disassemble Data for study, and when Data resigned rather than comply, Louvois convened a hearing to decide whether he was Starfleet property. William Riker was forced to argue against Data while Picard defended him, and Louvois ruled that Data had the right to choose for himself.