Student or Learner
Here's an excerpt from an article that ran in the Boston Herald:
Nate Robinson won’t be on the floor with his full team until tomorrow’s shootaround. But at least the new guard made it onto the floor yesterday.
Traded to the Celtics [team stats] from New York on Thursday (with Marcus Landry for Eddie House, Bill Walker and J.R. Giddens), Robinson has been fighting flu-like symptoms, which prevented him from joining the club out west.
Couldn't one make a strong case that "prevented him from joining the club out west" is a restrictive clause, and that there should hence be no comma before "which"? A restrictive clause is something that's essential to the meaning of a sentence, and that appears to be the case in the sentence above.