(Reuters) - U.S. Attorney General Jeff Sessions on Tuesday denied that he misled legislators when he previously failed to disclose a meeting he attended with then-candidate Donald Trump and aides where campaign connections to Russia were discussed. Sessions testified in Congress that, following a guilty plea by Trump campaign foreign policy advisor George Papadopoulos, he now remembers a March 2016 meeting at which Papadopoulos was present and suggested he could arrange a meeting with Russian President Vladimir Putin. Democratic Representative Ted Lieu, who sits on the House of Representatives Judiciary Committee, said on Twitter on Tuesday he believes Sessions committed perjury when he previously denied knowledge of contact between Trump’s campaign and Russia.  The following describes the crime of perjury and whether it would apply to Sessions’ conduct. What is perjury?     A person can be convicted of perjury only if they intentionally make a false statement under oath about a fact pertinent to a relevant investigation or criminal case. Under federal law the penalty for perjury is a prison sentence of up to five years or eight years in terrorism-related cases. “You can’t x-ray people’s minds to see what they were thinking and what they knew, so perjury can be a difficult crime to prove,” said Bennett Gershman, a professor of criminal law at Pace Law School.  Did Sessions commit perjury?     Some legal experts said there is a strong argument that Sessions committed perjury at an Oct. 18 oversight hearing before the Senate Judiciary Committee. During that hearing, Democratic Senator Al Franken asked Sessions whether “surrogates from the Trump campaign had communications with the Russians.” Sessions responded, “I did not, and I’m not aware of anyone else that did, and I don’t believe it happened.” Gershman said that Sessions’ failure to disclose the Papadopoulos meeting could amount to perjury. Perjury prosecutions based on congressional testimony are rare, in part because lawmakers often ask circuitous questions. But in this case Franken asked a straightforward question and the response Sessions gave was misleading, Gershman said. However, Stuart Green, a professor of criminal law at Rutgers University School of Law, said Sessions would have a plausible argument that Papadopoulos’ communications were not the type of contacts Franken was asking about since they were with Russian government intermediaries rather than Russian officials. “There’s a bit of wiggle room there,” Green said.     What if Sessions says he forgot about Papadopoulos’ remarks?     Sessions said at the hearing on Tuesday that he forgot about the March 2016 meeting because the Trump campaign was “a form of chaos” from the beginning. “We traveled all the time, sometimes to several places in one day. Sleep was in short supply,” he said. A prosecutor could use circumstantial evidence to undermine such a defense, lawyers said. Gershman said Sessions’ statement that he did not recall Papadopoulos’ remarks at the meeting would raise skepticism since Sessions led the meeting, Trump attended it and important national security matters were discussed. “It’s something a person would be hard-pressed to claim they don’t remember,” he said.      Who could prosecute Sessions for perjury?     Any charges against Sessions would likely be brought by Special Counsel Robert Mueller. Green said that Mueller’s mandate clearly encompasses looking into whether Sessions tried to conceal the extent of Russia’s influence in the election. But Gershman noted that Mueller may be reluctant to charge Sessions with perjury because the case would not be solid. “When you bring a charge against a high-profile figure you don’t want to lose because then it looks like a witchunt,” he said.     