I hate the way this discussion goes, as there are two reading into a law that utterly conflict, and I would like to know which is "objectively" the right one. Janur is someone who hates this type of discussion, and wants to know the actual facts first.
I see two possibilites:
reading one:
Guilty until proven innocent means that as soon as someone accuses a person of a crime, and the crime obviously has happened, that is the prime suspect and should be treated as guilty party, unless proven different.
This enables ANY citizen of Mikona to successfully accuse any person of a crime, but also makes life for the guards quite easy, as any crime is quickly solved, although perhaps often wrongly.
reading two:
Only an official of the city can accuse a person in a way that the accused needs to defend himself. Thus people can go and complain at the guards at any length. As long as the guardsmen don't want to listen, nothing happens. They have to formally accept these charges to let the "guilty until proven innocent" rule kick in.
This puts a lot more power into the hands of the guards, and may prevent false accusations, and also opens the possibilities of bribes. ("here, for 12 pieces of silver you won't listen to these complaints")
My request:
Can a DM please say which of these interpretations is correct ? Other players: Please DO NOT ARGUE HERE. If you think I've missed something, PM me and I'll edit my post to include your thoughts. Let's make it easy for the DM's here.

edit: */me sees the thread getting hijacked and abandons all hope of seeing a DM answer here.*