It's one of the odd twists of politics that not all political TV ads are created equal. Some are designed to be all about electing someone or defeating someone else, while others are meant to be about issues. It matters a lot to the outside money groups that are running the ads, but for the rest of us, it gets harder and harder to tell them apart.
The last time the Supreme Court looked at this question was in the Citizens United case in 2010.
Citizens United, a tax-exempt social welfare organization, argued that its film Hillary the Movie, essentially a character attack on then-Sen. Hillary Clinton, was not about her presidential bid.
In legal parlance, the Citizens United lawyer argued that the film was not express advocacy against Clinton's candidacy. But the Supreme Court didn't buy it, as Justice Anthony Kennedy explained on that decision day.
"We reject that argument. The film is quite critical of Sen. Clinton," he said. "We agree with the trial court that the film is susceptible of no other interpretation than to argue to the public that she lacked qualifications for the, for office."
So if that message was clearly political to the Supreme Court, how about this one?
This is an issue ad, as defined by federal election law. It comes from Crossroads GPS, the social welfare organization co-founded by Republican strategist Karl Rove.
Crossroads GPS President Steven Law says the group is in for the long haul, not just the election, and it's out to change policies in Washington.
"You can't achieve that merely by producing the TV equivalent of a policy white paper," he says. "You need to reach viewers viscerally, and so we spend a lot of time figuring out how to explain issues in ways that get viewers to be persuaded and also to get fired up to take action."
Crossroads GPS has been one of the most prominent political advertisers this spring. It has run ads attacking President Obama on a wide range of issues.
The donors who finance those ads get to stay anonymous, a big advantage for Crossroads GPS and other social welfare organizations, or 501(c)(4) groups as they're known in the tax code.
Political scientists say the line between issue ads and express advocacy has almost been erased.
Not so many years ago "we could more easily put particular ads into buckets," says Deborah Jordan Brooks, a government professor at Dartmouth College who studies political attack ads. "Ads that are largely issue-based often have a real personal zinger right in there, and it may just be one line. Or ads that, you know, really have a lot of personal zingers in there still have some issue content."
Campaign finance lawyer Robert Kelner says he is not surprised by the vagueness. Ultimately, he says, it's all about free speech.
"The price that we pay for the benefits of the First Amendment is that we have to essentially give a pass to some ads that you and I would probably agree look an awful lot like a campaign ad," he says.
But it still matters which side of the line a group is playing on. And here's a new paradox about that: A federal judge recently ruled that for certain types of issue ads, 501(c)(4)s have to name the donors.
The ruling hasn't taken effect yet.
But for now, some groups are switching to express advocacy ads. Kelner says that's risky because social-welfare organizations can't make politics their primary purpose.
"We don't know where the line is," he says. "We don't know how many ads the (c)(4) could run before it would jeopardize its (c)(4) status."
Without 501(c)(4) status, an organization would lose the thing that gives it so much political clout: the ability to take anonymous contributions.