Donald Trump also encouraged his Twitter followers to shop at the New England retailer, known for preppy outdoor apparel, and included the Twitter handle of Perfect Maine, a lobster-themed business owned by Judy Bean. Here’s the tweet:

Thank you to Linda Bean of L.L.Bean for your great support and courage. People will support you even more now. Buy L.L.Bean. @LBPerfectMaine

— Donald J. Trump (@realDonaldTrump) January 12, 2017

Needless to say, the Trump stamp of approval set off a storm of attention on social media. Not all of it was good, however, as an anti-Trump group called Grab Your Wallet threatened a boycott of L.L. Bean and individual consumers vowed to shun its merchandise. But overall, it’s safe to say L.L. Bean and the once-obscure Perfect Maine earned more free publicity than they have in years.

But regardless of the public relations implications, some are asking how this can even be legal. After all there are federal laws about endorsements, including endorsements on social media:

I think some kind of disclosure is required for this sort of sponsored tweet, isn't it @FTC? https://t.co/9BlTHDTrta

— Mathew Ingram (@mathewi) January 12, 2017

So did Trump do anything wrong? In one respect he’s in the clear. While the Office of Government Ethics, which monitors conflicts of interest in the executive branch, says endorsements are not allowed, the rules do not apply to the president or president-elect.

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But that’s not the end of it. There’s also the Federal Trade Commission, which has been aggressive about requiring celebrities and companies to disclose when they endorse products on platforms like YouTube, Twitter, and Instagram. In the last two years, the agency has taken action over social media plugs by Kim Kardashian and others that failed to include “#spon” or other marks to show a commercial agreement.

Trump’s endorsement of Perfect Maine, in particular, may violate the FTC rules given that Linda Bean has, as the New York Times reports, donated $60,000 to a pro-Trump political committee. If it is a violation, it’s unclear who would be held responsible since, in the past, the FTC has filed complaints against the companies that received the endorsement rather than against the celebrity who made them.

And in the event Trump turns out to be exempt from the FTC rules in his position as president-elect, there’s also the question of whether the same exemption protects Trump’s corporate interests.

Reached by phone, a spokesperson for the FTC said the agency did not wish to comment at this time.

So, as with the suddenly vogue “Emoluments clause” of the U.S. Constitution, the law of endorsements, when it comes to the president, are not clear. For now, it’s only safe to say the L.L. Bean is unlikely to be the last debate over Trump and conflicts-of-interest for the foreseeable future.