[SketchySeaBeast]

Doesn't that feel more like it should be described as "not explicitly illegal"? Saying that the reason must be legal gives it the sense that there is a list of valid reasons you could fire someone when, as I understand it, that list doesn't exist, and there's strictly a list of reasons you can't. "You wore green shoes so you're fired" is a reason that someone can be fired, but to say it's a legal reason gives it weight such a frivolous dismissal doesn't deserve.