A million (okay: a little more than five) years ago I wrote in asking about jails, prisons, and how long you spend in them before you're tried. Yes, it's been five years, but I'm thinking about getting back to this thing, and I found the old post (yay!), and ... as near as I can tell reading the comments, they talk about where you go and how long you spend there once a formal charge has been brought against you. (I gather that like us in the United States, in the UK you are also entitled to a speedy trial ... and that what the courts consider "prompt" and "speedy" is often different to what civilians expect.)
What I still can't tell if I know is this: how long can they normally hold you before they have to formally charge you with something or let you go? Uncle Wiki seems to suggest it's normally 24 hours, with special circumstances making it possible to hold a person for 36 or even 38 hours - but in even special-er circs if the person is suspected of certain terrorism-related offences they can be held for as long as seven days before even being arraigned. So supposing it's the early 21st century and I'm locking Snape up--in what has turned out, over the years, to be a slight alternate universe--for crimes committed during the first Voldemort administration in the 1980s. [That is, there was def. a crime committed and they're holding Snape while they try to pin it on him.] On about the fourth day (as I've got it now), Another Character visits him in prison [in the remand area, apparently] and says, at one point, "Yes, you want me to be your star witness, but who's actually working on your defence? Who's representing you?" and Snape says "There's still been no charge." Of course one is horrified by this, but assuming they arraign him by about day six, is it completely out of the question?
What sort of defense lawyers do you suppose wizards have? (What sort of prosecutors, for that matter. Presumably there's a prosecution department at the Ministry - but as the Minister of Magic doesn't seem to be a part of the Queen's Government, who knows if his lawyers are crown prosecutors or what.)