Filing a lawsuit in a foreign nation costs six figures and up up up, exposes you to the substantial risk of losing due to home court advantage, and gives you the upside that the fly-by-night developer who stole your idea gets told in a very stern tone of voice to please not do it again. It is not a realistic way for you to cover the downside risk of getting your code stolen.

Want good news? Your idea is worthless, so it is no biggie if it gets stolen. The source code produced is likely to be overvalued at "worthless", so if one of your competitors gets a hold of it, you'll quickly be ahead of the game as long as you don't do anything excessively stupid like attempting to use that source code yourself. (You may succeed in getting code with actual value if you're really good at both picking your provider and managing the outsourcing project, which is ahem not a cheap, easy, do-in-your-spare-time endeavor.) No company worth building is at risk of getting knocked off by a cheap outsourcing company -- if all it took was enough monkeys banging on typewriters to make a software company, they'd already be doing it.

My bona fides: managed outsourcing operations for a few teams of a Japanese multinational for a few years.