Penn – enacting the real-life role of a reporter for Rolling Stone – conducted what he apparently hoped would be a clandestine interview in October with Guzman, who was hiding in Mexico after escaping a maximum security prison there in July. Penn's account of the meeting was published online Saturday, a days after Guzman was arrested in a raid by Mexican authorities that killed five.
The question now is whether Penn will face charges for his dealings with Guzman, who was a fugitive from American authorities on drug trafficking charges.
Georgetown University Law School Professor Paul Rothstein, an expert in criminal law and procedure, tells PEOPLE that knowingly visiting a fugitive is not a crime:
"There is no criminal liability for seeing something illegal and not reporting it." He added, "If Sean Penn did nothing more than visit and report, he is protected by the First Amendment, and is in the clear."
If, however, Penn arranged profit or gain for Guzman – Guzman allegedly met with Penn because he was interesting in making a biopic about his life – the actor could be in trouble.
"A prosecutor could frame that as aiding and abetting," Rothstein says.
Whether Penn is liable or not hinges on intent, legal experts say.
"A lot will depend on how the meeting was arranged, and the entire purpose for which he went," says Wisconsin-based lawyer Mary Lou Woehrer, who represented Lawrencia "Bambi" Bembenek, a convicted American murderer who escaped prison and fled to Canada in 1990.
Law Professor: If Charged, Penn Could Strike a DealPenn has received criticism for the interview, with some saying that he glamorized Guzman. In a brief email to the Associated Press on Monday, Penn wrote, "I've got nothin' to hide."
A Drug Enforcement Agency agent, speaking on the condition of anonymity, tells PEOPLE, "It's tempting to say that a moral transgression is a criminal act, but one does not automatically equal the other."
If Penn is charged, Rothstein believes he can play a valuable card: "He perhaps has a little something that he knows," Rothstein posits. "He could strike a deal."
The possibility of uncovering criminal behavior from Penn seems unlikely, Woehrer says. "The visit seems pretty innocuous to me."
Even if Penn is deemed innocent of wrongdoing, he still could wind up in court as a witness in proceedings against Guzman, the DEA agent says.
"That is almost guaranteed," the agent says.
The New York Post, meanwhile, reports that Manhattan prosecutor Preet Bharara is exploring possible ties between Penn and Guzman, and is seeking a subpoena for the actor's cell phone records.
The office of another U.S. Attorney, where charges are pending against Guzman, is playing its own cards close to the vest.
"There is nothing I can say publicly," says Joe Fitzpatrick, a spokesman for the U.S. Attorney's office in Chicago.