Donald Trump says he "can't" release his tax returns because he's being audited. But there's not actually any legal restriction on doing so.

Trump has come under pressure recently to release his personal tax data after former GOP nominee Mitt Romney began suggesting that there might be a "bombshell" lurking in the information, and that Trump might have something to hide.

That's pretty ironic, given that questions about Romney's tax returns dogged him throughout the 2012 presidential election, especially after Harry Reid said he'd heard from an unnamed source that Romney didn't pay any taxes at all. This, of course, turned out not to be true. What Romney is doing to Trump, in other words, looks a lot like what Reid did to Romney.

But Romney has forced Trump to respond. At last night's GOP debate, Trump was asked about whether he'd release his returns. Trump said he wanted to release his returns, but that he was under audit.

After a follow-up from moderator Hugh Hewitt, Trump said: "I want to release my tax returns but I can't release it while I'm under an audit. We're under a routine audit. I've had it for years, I get audited. And obviously if I'm being audited, I'm not going to release a return."

But as Politico reports, nothing in the law prohibits him from releasing his returns. And not all of his taxes are being audited.

Stanford law professor Joseph Bankman said it's not so odd for a man of Trump's wealth to be subjected to repeated audits. "A lot of super wealthy individuals, and all large companies, are audited every year," Bankman said Thursday night. But he said Trump's statement that he "can't" publicly release his returns is a headscratcher. "I'm not sure why that prevents him from releasing his returns. They are his to release," Bankman said. While tax returns are confidential by law and can't be released by the IRS, there's no legal restriction on Trump publicly releasing his own forms if he sees fit. Also, some of Trump's past returns are not under audit. At this point, he hasn't released those either.

It is possible, given Trump's penchant for descriptive imprecision, that when Trump said, "I can't release it while I'm under an audit" he meant something other than, "I am legally prohibited from doing so."

But it's unclear what that something else might be, and hard to imagine that anything else would really qualify as a restriction making him unable to release his returns. What it sounds like, then, is that when Trump says he can't release his returns, what he really means is that he won't.