We get a lot of daft Muslim scare stories in some parts of the press here in the UK, "sharia law" being one of the favourites - this article in the Guardian tries to point out the reality:
http://www.theguardian.com/world/2014/may/12/muslim-scare-st...
On closer inspection, it is clear sharia courts only have jurisdiction on civil matters and everyone must opt in to a sharia court. They only have an advisory capacity and address mainly property and financial matters, and rulings are then only enforceable by civil courts. In many cases, they are understaffed affairs, where one official settles petty disputes and draws up rudimentary documents.
So just like any other kind of alternative dispute resolution - mediation, adjudication, expert-determination, arbitration etc.
Edit - I'm actually over-stating this last bit, "sharia" law isn't nearly as strong as these formal ADR mechanisms.