President Donald Trump’s fresh acknowledgement that his top campaign advisers met at Trump Tower in July 2016 with Kremlin-connected Russians to “get information on an opponent” has renewed questions about whether his son Donald Trump Jr, who arranged the encounter, is facing legal trouble.

The president blasted as “fake news” a Washington Post article that said he was fearful that Donald Trump Jr “inadvertently may have wandered into legal jeopardy”. He also tweeted on Sunday that seeking opposition research was “totally legal” and “done all the time in politics”.

And Jay Sekulow, one of the president’s lawyers, said in an interview on ABC’s ‘This Week’ that “the question is what law, statute or rule or regulation’s been violated?”

“Nobody’s pointed to one,” he said.

Here is a look at some ways Donald Trump Jr may be in legal jeopardy.

Did he engage in ‘collusion’?

“I did not collude with any foreign government and did not know anyone who did,” Donald Trump Jr told the Senate Judiciary Committee in September 2017. But his participation in the Trump Tower meeting with the Russians, as well as another meeting, has put that claim under scrutiny.

Ahead of the meeting with Russians, an intermediary promised Donald Trump Jr that a “Russian government attorney” would provide “very high level” dirt on Hillary Clinton as “part of Russia and its government’s support for Mr Trump”. He wrote back, “If it’s what you say I love it.”

In a meeting three months before the election, Donald Trump Jr met with another small group offering to help his father win the election. It included an emissary for two wealthy Arab princes who run Saudi Arabia and the United Arab Emirates, as well as an Israeli specialist in social media manipulation. The younger Trump responded approvingly, a person with knowledge of the meeting told The New York Times.

Participants in the meeting with the Russians have testified that nothing came of it, and it is unclear whether any assistance came out of the second gathering, either.

Did he engage in a ‘conspiracy’?

In plain English, “collusion” means working together, usually in secret, to do something illicit. But the word has no defined legal meaning. This is apparently why the president has been declaring that “collusion is not a crime,” as he tweeted last Tuesday.

That is irrelevant, however, because lawyers instead talk about conspiracy: an agreement by two or more people to commit a crime – whether or not they end up doing so. A powerful tool for prosecutors, conspiracy charges allow them to hold each conspirator responsible for illegal acts committed by others in the circle as part of the arrangement. To convict someone of such a conspiracy, prosecutors would need to obtain evidence of an agreement to commit a specific crime.

Was the law broken?

A provision of the Federal Election Campaign Act, Section 30121 of Title 52, broadly outlaws donations or other contributions of a “thing of value” by any foreigner in connection with a US election – or even an express or implied promise to take such action, directly or indirectly.

Depending on how a grand jury interprets the facts the special counsel, Robert S. Mueller III, has gathered about the two Trump Tower meetings, it could find that the foreigners violated that law – and that Donald Trump Jr conspired in that offence.

Trump in Helsinki: Putin meeting and protests Show all 16 1 /16 Trump in Helsinki: Putin meeting and protests Trump in Helsinki: Putin meeting and protests President Trump meets with Russian President Vladimir Putin in Helsinki Reuters Trump in Helsinki: Putin meeting and protests An advert from Finnish newspaper Helsingin Sanomat is on display in Helsinki Reuters Trump in Helsinki: Putin meeting and protests President Trump in a meeting with Finnish President Sauli Niinisto AFP/Getty Trump in Helsinki: Putin meeting and protests President Trump meets with Finnish President Sauli Niinisto in Helsinki EPA Trump in Helsinki: Putin meeting and protests President Trump talks with Finnish President Sauli Niinisto in Mantyniemi, the official residence of the Finnish President EPA Trump in Helsinki: Putin meeting and protests US, Finnish and Russian flags fly in front of the Presidential Palace in Helsinki EPA Trump in Helsinki: Putin meeting and protests A protester wears a mask featuring a portrait of Russian President Vladimir Putin during the so-called "Helsinki against Trump and Putin" demonstration on July 16, 2018, in the Finnish capital Helsinki. The US and Russian leaders opened an historic summit in Helsinki on Monday, with Donald Trump promising an "extraordinary relationship" and Vladimir Putin saying it was high time to thrash out disputes around the world. / AFP PHOTO / Jonathan NACKSTRANDJONATHAN NACKSTRAND/AFP/Getty Images JONATHAN NACKSTRAND AFP/Getty Trump in Helsinki: Putin meeting and protests Vladimir Putin gifts a football to President Trump at the press conference that followed their meeting AP Trump in Helsinki: Putin meeting and protests Trump supporters hold banners during a demonstration in Helsinki AFP/Getty Trump in Helsinki: Putin meeting and protests People protest for women's reproductive rights in Helsinki's Senate Square Reuters Trump in Helsinki: Putin meeting and protests A crowd watches the motorcade transporting President Trump through Helsinki AFP/Getty Trump in Helsinki: Putin meeting and protests Russian President Putin drives through Helsinki on his way to meet with President Trump EPA Trump in Helsinki: Putin meeting and protests A man in the audience of the joint press conference holds up a sign sign that reads "NUCLEAR WEAPON BAN TREATY". REUTERS Trump in Helsinki: Putin meeting and protests A man is removed from the joint press conference in Helsinki. Security removed the man after he pulled out a sign that read "NUCLEAR WEAPON BAN TREATY". REUTERS Trump in Helsinki: Putin meeting and protests President Trump and Russia's President Putin sit for a working lunch in Finland's Presidential Palace AFP/Getty Trump in Helsinki: Putin meeting and protests President Trump meets with Russian President Vladimir Putin in Helsinki Reuters

Another provision of the same statute makes it illegal for an American to solicit a foreigner for such illicit campaign help – again, even indirectly. If a grand jury were to interpret the evidence about Donald Trump Jr's words and actions as a solicitation, he could also be vulnerable to direct charges under that law, experts said.

Notably, the statute can be violated even if the promised or requested help is never provided.

But does opposition research count?

Legal experts have struggled to identify a precedent for criminally charging somebody under this law. As a result, an attempt to prosecute Donald Trump Jr under that statute would raise novel issues.

Americans may have a First Amendment right to ask foreigners for opposition research information, Eugene Volokh, a professor at the University of California, Los Angeles, has argued. Others disagree.

It is also not clear whether opposition research counts as a “thing of value”. Courts have held, in bribery and threat cases, that a “thing of value” can be something intangible, like information, noted Richard L Hasen, an election-law professor at the University of California, Irvine.

And Robert Bauer, a New York University election-law professor who served as White House counsel in the Obama administration, argued that the statute against foreign campaign assistance is so broadly worded that its covers Russia paying spies and hackers to collect and disseminate negative information about Clinton to help Trump win the election – even expenses like their travel for the meeting.

But applying that law to negative information about a political candidate is a stretch, said Orin S. Kerr, a University of Southern California professor and former federal prosecutor.

“The phrase ‘contribution or donation’ sounds like a gift to help fund the campaign or give them something they otherwise would buy,” Mr Kerr said.

What about conspiracy to defraud the United States?

Legal experts analysing the younger Trump’s actions have also pointed to another, less discussed part of the federal conspiracy statute. It prohibits conspiracies to defraud the United States by impeding the federal government’s lawful functions.

Notably, Mr Mueller has already relied on that statute in a similar context. In February, when a grand jury indicted 13 Russians and three Russian organisations accused of undertaking a covert operation to manipulate US social media and help the Trump campaign, the charges included conspiracy to defraud the United States.

Specifically, they were accused of preventing the Federal Election Commission from fulfilling “its statutory duties of providing the American public with accurate data about the financial activities of individuals and entities supporting federal candidates, and enforcing limits and prohibitions, including the ban on foreign expenditures.”

What About Making a False Statement?

It is a felony to lie to Congress. In his September 2017 interview before the Senate Judiciary Committee, Donald Trump Jr was asked whether any other foreign governments or nationals offered assistance to the Trump campaign, or whether he had directly or indirectly sought such foreign assistance for the campaign. He said he had not.

In May, after The Times reported about the meeting with the emissary for the Arab princes and the Israeli social media manipulation specialist, Sen. Chris Coons, D-Del, raised concerns that Mr Trump may have lied to the committee.

The Judiciary Committee chairman, Sen. Charles E. Grassley, R-Iowa, pushed back, suggesting that “there are potentially innocuous explanations”.