
The interplay between collective bargaining and “rules of the game” is a complicated one. Timeouts, of course, seem a bit like "hours." Of course, banning time outs might actually reduce the hours that an NBA player spends “in the building.” Still, something that decreases hours at work would seem to "concern" hours. Similarly, to the extent that eliminating timeouts changed the “conditions” under which NBA games were played (by making the end-game a more continuous, high-paced experience) such a move would seem to fall into the mandatory category. I imagine that many of the more hulking and less limber NBA players would be concerned that a timeoutless 4th quarter would involve a higher risk of injury, since play would necessarily become more chaotic and unpredictable.
The leading sports law casebooks pose some interesting hypotheticals about the mandatory vs. permissive distinction in connection with rules and conditions of play. For example, the Mitten/Davis/Smith/Berry book Sports Law and Regulation: Cases, Materials & Problems offers: the placement of the 3-point line in basketball; the height of the pitcher’s mound in baseball; the dimensions of a hockey rink or baseball field; and the status of the DH rule in baseball (page 576). The Weiler/Roberts book Sports and the Law: Text, Cases & Problems offers: the DH rule; institution (or elimination) of overtime to break ties in hockey or football; installation of artificial turn in football or baseball parks; hockey’s rule about wearing helmets during games; and the use of instant replay (page 327).