Most of the public discussion about the Russia investigation centers on the question of collusion between Moscow and the Trump campaign to undermine Clinton. But “collusion” isn’t a specific crime under federal law. Instead, legal experts have questioned whether any Trump campaign officials may have violated a campaign-finance statute that bars foreigners from donating money or any other “thing of value” to a campaign. That same provision also forbids campaign officials from soliciting such a donation.

“If I’m a foreign citizen and I give a thousand dollars to the campaign, then that’s a thing of value,” Hasen explained. “If I provide a dossier, that also could be [a thing of value]. And so the question that came up during the last Don Jr. controversy was whether providing dirt on Hillary Clinton—opposition research—could be a thing of value for purposes of the statute.”

That debate first arose in July when The New York Times revealed that Trump Jr., his brother-in-law Jared Kushner, and then-campaign Chairman Paul Manafort met with Russian lawyer Natalia Veselnitskaya in Trump Tower in June 2016 after she promised “information helpful to the campaign” about Clinton. Trump Jr. denied any wrongdoing and said that Veselnitskaya, who has ties to the Kremlin, provided no such information to them.

The Twitter conversations made public so far don’t show deliberate solicitation of WikiLeaks’s help on the part of Trump Jr. The closest he came to such a request was on October 3, 2016, when he asked WikiLeaks, “What’s behind this Wednesday leak I keep reading about?” (Roger Stone, an occasional Trump adviser, had tweeted “Wednesday@HillaryClinton is done. #WikiLeaks.” the day before.) Indeed, it was WikiLeaks that solicited from Trump Jr. throughout the exchanges—asking for his father’s tax returns, highlighting links for Trump Jr. to tweet, and even suggesting that the elder Trump publicly float Assange as a possible Australian ambassador to the United States.

Even if the exchanges did show Trump Jr. soliciting damaging information from WikiLeaks, federal prosecutors could run into difficulty pursuing charges for violating foreign-spending rules. “Assange is or could be considered a journalist, and we might have different rules for foreign-news media,” Hasen explained. “Certainly that’s how domestic campaign-finance law works, where we treat media differently than others.” And while he believes that a “thing of value” under the statute can include opposition research or stolen emails, that view isn’t unanimous among legal experts. He cited arguments made in July by Eugene Volokh, a UCLA law professor, that such a broad interpretation of the term could run afoul of the First Amendment.

Trump Jr.’s messages also show WikiLeaks providing him with the login information of an anti-Trump website. “A PAC run anti-Trump site putintrump.org is about to launch,” the account wrote to Trump Jr. “The PAC is a recycled pro-Iraq war PAC. We have guessed the password. It is ‘putintrump.’ See ‘About’ for who is behind it. Any comments?” Trump Jr. replied that he would “ask around” about the website’s provenance.