By birth, all drow are granted citizen status in Yethendrin, but are consequently put under the authority of the Priestesses of Lolth. Barring crimes against the drow people themselves (blasphemy, mass drow genocide, etc.) the expectation is that lesser matters are settled by vendetta and blood-right between Houses. Drow with no tie to even a Lesser House consequently have to watch their actions. If they’re lucky enough to find a House to advocate on their behalf, they have more freedom to seek reprisal for injury or sleight done to them.
A non-drow earns citizenship through sponsorship by a noble drow house, diplomatic credentials or political maneuvering, or sometimes through utility or fame. Service in the armies of the Vault grants citizenship, and bribery presents another avenue for the wealthy. Non-drow citizens fall under the secular authority of the Empyrean, whose rule over them is passive, at best. In general, the assumption is that non-drow can offend and kill each other to their heart’s content so long as it does not disrupt the general day-to-day function of Yethendrin. A non-drow who harms or kills a drow will likely be hauled before the Empyrean for justice, or tried before one of her subordinates in the byzantine Court of Grievances, where bribery and wealth often win the day.
Non-citizens face the most complications. These are those “foreigners” who have come to the Vault to trade, in pursuit of information, or entirely accidentally. They must take care, as they have little to no protection under the law, and can face reprisal for even entering the Spider Quarter (home of most of the city’s drow). Worst of these are those who come to Yethendrin in chains, or else were born to slavery. Slaves are the lowest of the low, having little legal right at all. Killing a slave might result in having to pay a fine to its owner, though a favored slave can be treated as any other prized property, and result in vendetta. Slaves tread lightly, and rely on the favor of their masters to ensure their continued survival.