Throughout Star Trek, legal and quasi-legal proceedings from court martials to arbitration (see the TNG episode "Devil's Due") use members of the crew as lawyers. Obviously, in real life, this is because the stars of the show are the people who the producers want on-screen.
However, in universe, why does the flagship of the Federation, which adheres (in theory) to the rule-of-law, not carry lawyers like real life militaries do? For example, in real life, a US Navy aircraft carrier has three JAGs on it to give legal counsel to the officers in conducting their duties. For remote outposts like DS9, it is understandable why there might not be a full complement,but it seems ridiculous that Riker has to step in as a defence counsel (TNG: "The Drumhead") or Troi has to analyse treaties for loopholes ("The Ensigns of Command")?
Are there any in-universe reasons as to why a ship that can afford to have full-time civilian bar proprietor and several civilian waiters ("Lower Decks"), a barber, and a number of pets doesn't have a lawyer, especially when that is standard practice in most democratic countries' navies today?
