WASHINGTON — Calls to prosecute the founder of WikiLeaks, Julian Assange, mounted this week as his organization began releasing documents from a cache of 250,000 State Department cables — its third major disclosure of United States government secrets this year.

Attorney General Eric H. Holder Jr. has confirmed that the Justice Department is examining whether Mr. Assange could be charged with a crime, but legal scholars say that such an effort would encounter steep legal and policy difficulties.

“There is a haze of uncertainty over all of this,” said Stephen I. Vladeck, an American University law professor who has written about the Espionage Act, a 1917 law that prohibits the unauthorized retention or transmission of defense-related documents.

“The government has never brought an Espionage Act prosecution that would look remotely like this one,” he said. “I suspect that has a lot to do with why nothing has happened yet.”

The Obama administration has been scrambling to figure out how to respond to the WikiLeaks disclosures. On Wednesday, the White House national security team appointed an official, Russell Travers, to coordinate “technological and/or policy changes to limit the likelihood of such a leak recurring.”

Legal scholars say the legal landscape for the protection of government information has been exposed as unprepared for the mass dissemination of leaked electronic documents on the Internet.

A relic of World War I, the Espionage Act was written before a series of Supreme Court rulings expanded the First Amendment’s protection of speech and press freedoms. The court has not reviewed the law’s constitutionality in light of those decisions.

Moreover, in a reflection of strong constitutional protections for the freedoms of speech and the press, the United States has usually prosecuted only government officials responsible for leaking documents, not outsiders who received information and passed it on.

The one effort to prosecute recipients of a leak under the Espionage Act ended in embarrassment for the Justice Department. In 2005, it indicted two lobbyists for a pro-Israel group who had been accused of receiving leaked information from a Pentagon official and conveying it to others. The case collapsed after a judge ruled that prosecutors had to prove that the lobbyists specifically intended to harm the United States or benefit a foreign country.

That ruling, specialists say, suggests that prosecutors would have to prove that Mr. Assange intended to harm the United States. That could be difficult. While he has made many statements critical of United States foreign policy, he has also portrayed himself as motivated by a belief in greater openness.

Prosecuting Mr. Assange could also open the door to prosecuting traditional media organizations, including The New York Times, which was provided advance access to the materials.

Although legal scholars say the law does not draw a legal distinction between the traditional news media and anyone else, Justice Departments under both political parties have been reluctant to prosecute members of the press.

Jack M. Balkin, a Yale professor of constitutional law, noted that Mr. Assange had portrayed himself as a journalist, calling himself an editor who received unsolicited information and made decisions about how to publish it.

“If you could show that he specifically conspired with a government person to leak the material, that puts him in a different position than if he is the recipient of an anonymous contribution,” Mr. Balkin said. “If he’s just providing a portal for information that shows up, he’s very much like a journalist.”

There are indications that the Obama administration may be taking steps toward a potential prosecution of Mr. Assange by establishing a record that he was on notice that the law required him to return the documents rather than distribute them.

Two administration lawyers have written letters informing him that publishing the materials would have grave consequences and that “as long as WikiLeaks holds such material, the violation of the law is ongoing.”

But in an interview with Time magazine, Mr. Assange rejected such warnings, questioning the constitutionality of the Espionage Act. He said it was important to remember that the law was “not simply what powerful people would want others to believe it is.” Rather, he said, the law is what the Supreme Court “says it is, and the Supreme Court in the case of the United States has an enviable Constitution on which to base its decisions.”

There are other legal impediments. It is not clear where Mr. Assange is, and extradition may be difficult. An extradition treaty with Britain, for example, gives British judges the authority to reject an extradition request for “political” charges.

Moreover, Mr. Assange is an Australian citizen. Still, Mr. Holder said Monday that he did not believe that Mr. Assange’s citizenship or location was a barrier to prosecution.

“To the extent there are gaps in our laws, we will move to close those gaps, which is not to say that anybody at this point, because of their citizenship or their residence, is not a target or a subject of an investigation,” he said.