[mathattack]

Anyone can make a suit. (I've been on the receiving end of a frivolous one where the employee was caught committing fraud and sued anyway.) Frequently it's just cheapest for everyone to settle. A court date with expensive lawyers can cost more than a month's salary.

The law generally doesn't require a reason or documentation unless the employee is a protected class. If you are still positive with your boss or the CEO, you can usually ask off-line if you've signed something that says you won't sue.