here to make sense of it for us is marcia coyle of the national law journal.come back. >> thanks. >> woodruff: what prompted the justices to take up this challenge to the healthcare law, another one? >> usually, the court waits for disagreement in the lower federal appellate courts before it takes a case. that's one of the criteria for review. technically there is no division right now, but the court will also step in if the issues of national importance or if it's an issue that could likely recur and, certainly, there are other cases pending that are challenging this particular provision in the affordable care act. >> woodruff: so what do you think prompted this? i mean, the assumption is that the four more conservative justices who were not on board with the 2012 ruling that upheld most of the affordable care act were behind this. what's the thinking? >> well, we really don't know the votes, who voted how to take review of this particular case. we do know that you only need four votes, and the speculation is that, at least among whoever did vote, there were