SportsLawBlog links to an interesting story about the Cameroonian soccer (football) team and a dispute over one-piece uniforms they are wearing:

Cameroon has been fined US$154,000 and was docked six points from their World Cup qualifying group for wearing a one-piece Puma uniform during the recent African Cup of Nations in Tunisia. Apparently, FIFA warned the team beforehand that the uniform was not sanctioned, but team wore it anyway. Cameroon disputes this, saying that the warning came too late for replacement uniforms could be produced. Puma, the manufacturer, claims that the uniform violates no rules of the sport. With regard to basic equipment that a footballer must wear, Law 4 of the Laws of the Game states: 'The basic equipment of a player is a jersey or shirt, shorts, stockings, shinguards, footwear'. "Nowhere in the rules is it mentioned that shirts and shorts (must be kept separate)," added Widmann. Puma has indicated that it will take FIFA to court over the ruling.

There's more to this than meets the eye. As you can see from the photo here the top part of the uniform is skin tight. Any soccer/football fan knows that grabbing, pulling and tugging on an opposing player's jersey is part of effective defense. My hunch is the bigger problem isn't so much over the fact that the unis are one piece, but that there's no way for opposing players to grab the jerseys. Of course, if it's one piece there's no shirttail to grab. That's the real issue here.