There’s been some chatter today about the new Pew poll finding that Americans won’t be happy with any of the possible Supreme Court rulings on Obamacare. A plurality of 48 percent won’t be happy if the entire law is tossed out; 51 percent will not be happy if just the mandate is struck down; and the same majority will not be happy if the law is upheld.

But now that repeal is a very real possibility, this finding may be the most dispiriting one of all:

Many Americans do not have a clear understanding of what’s in the health care law. About one-in-five (18%) say they understand the law very well and 49% say they understand it somewhat well; nearly a third (31%) say they understand it not too well or not at all well.

In broad terms, the poll finds that the percentage who will be unhappy if the mandate is tossed out is highest among those who say they know the law well, and lowest among those who don’t. It’s not easy to say what this means, because of the way the polling questions are constructed, but it seems possible that the lack of understanding of the mandate’s basic function within the legislation is one key cause of unhappiness with the provision or with the overall law.

After all, multiple polls have also shown overwhelming support for the provision that the mandate is designed to enable — the ban on discrimination against people with preexisting conditions. But the mandate is unpopular. Dems never successfully persuaded the public that it is necessary to sustain the preexisting conditions piece. More broadly, fewer than one in five say they understand the law very well. And the 49 percent who say they understand it “somewhat well” may be overstated, too.

You can chalk this up to a failure of messaging by Dems, or to their failure to include provisions the public clearly liked (see option, public) or to the right’s very successful sowing of confusion about the law, or a combination of all of those. Or perhaps, as Alec MacGillis writes today, the decision to have the major provisions kick in four years after passage has meant that Americans didn’t get to experience the law’s benefits firsthand, meaning that “its promises have not been clearly conveyed to the people it is designed to help.”

Whatever the reason, if the Supreme Court does strike down the law, it could recede into history even as millions and millions of Americans never learn what was actually in it — let alone how it might have benefited them.