Crime and Punishment
Most crimes in the underground are handled in a similar style to the town meetings. The concept of a “fair trial” has mostly been carried down from the initial refugees of the Overground.
Crimes are subjective in the Underground. Whilst it's unanimous that things like murder are bad, it's more subjective whether smaller things like anti-social behaviour and petty theft are punishable crimes, or are just a cause for the society to look out for each other more.
As for the trials, whilst there are few (if any) dedicated lawyers in the underground, due to trials being fairly rare, there are volunteer lawyers. The Director’s Office will be consulted for a final say on the trials, but this is mostly a formality; the Office is so busy, after all, that instead the trials come down to a popular vote.
The conduct of trials is somewhat comparable to a modern trial, there is time for the prosecution first, then the defence, and then the Judge/Jury ruling. However, due to most people living busy lives, it is a much more accelerated process, typically the trial itself not lasting more than a day.
To call a trial, you simply have to rally a crowd in the centre of Terminus. The crowd must be at least 30 people to constitute a valid trial. Any decision taken, either by majority or by the Director, is deemed final, unless the Director can be convinced to undo the sentencing.
Public trials are a measure of last resort, and it is far more common for interpersonal grievances, including minor crimes, to be resolved by simply asking the perpetrator to fix whatever they did.
If there is a trial, any punishment is theoretically possible as long as it is voted on. As the death punishment is generally frowned upon in this tight knit community, the most severe punishment to date has been exile with provisions—so severe, in fact, that this has only ever happened once in the history of the Underground. This happened about 10 years ago, with the exile in question being sent to one of the outer periphery stations. Nothing has been heard from them since. Common punishments include fines, which usually result in forfeiting possessions, and community service.