What does CBA say about situations like Malcolm Butler's?

Wednesday's news that New England Patriots cornerback Malcolm Butler had been held out of on-field practices for at least two weeks because he was late for the team's opening OTA (a result of a canceled flight the night before the workout) sparked several questions.

One of them was simply, "Can a team even do that to a player in a voluntary setting?"

Section 21 of the collective bargaining agreement touches on this area. Under the miscellaneous subheading (5a), it reads, "No Club official may indicate to a player that the Club's offseason workout program or classroom instruction is not voluntary (or that a player's failure to participate in a workout program or classroom instruction will result in the player's failure to make the Club or result in any other adverse consequences affecting his working conditions)."

In this case, it's the final 10 words that figure to catch the attention of the NFL Players Association as they relate to Butler, who isn't contesting anything personally and is viewing it as a learning experience.

Essentially it comes down to this: If a coach decides he doesn't want a player participating at a voluntary practice, could the NFLPA dictate otherwise?

It might be the first time this type of situation has ever come into play.