Will Obama live up to long-promised transparency?

President Obama expected to announce changes in speech at Justice Department

Panel recommended in December that government better protect civil liberties

Leaks by Edward Snowden exposed scope of NSA electronic surveillance

Congress is considering changes to national security laws as well

(CNN) -- President Barack Obama is expected to announce changes on Friday to sweeping U.S. surveillance efforts exposed by intelligence leaker Edward Snowden, whose blockbuster disclosures have raised questions about government overreach in fighting terror.

The scope of phone and e-mail snooping by the National Security Agency that came to light last year triggered outrage from civil libertarians and prompted key members of Congress from both parties to weigh changes in national security law.

Obama is expected to act on recommendations from an independent panel that he called for at the height of the fallout from the leaks around the agency's surveillance activities and a secret court that works with it.

The presidential Review Group on Intelligence concluded in December that data collection should remain but that the government must do a better job of protecting civil liberties in the context of national security.

What's the impact of NSA data collection?

National Security Agency leaker Edward Snowden poses with German Green party parliamentarian Hans-Christian Stroebele in Moscow on October 31. Stroebele returned from the meeting with a letter from Snowden to German authorities, which was distributed to the media. In it, Snowden said he is confident that with international support, the United States would abandon its efforts to "treat dissent as defection" and "criminalize political speech with felony charges."

Snowden's refugee document granted by Russia is seen during a news conference in Moscow on August 1. Snowden slipped quietly out of the airport after securing temporary asylum in Russia, ending more than a month in limbo.

Sen. Charles Schumer, D-New York, leaves a last-minute news conference at the U.S. Capitol after Russia announced that it would grant Snowden temporary asylum on August 1. "Russia has stabbed us in the back, and each day that Mr. Snowden is allowed to roam free is another twist of the knife," he said.

Snowden's father, Lon Snowden, who has adamantly supported his son, talks to reporters in Washington on Tuesday, July 30. He has urged his son to remain in Russia "until we have assurances that he would receive a fair trial."

Demonstrators in Berlin hold a protest march on Saturday, July 27, in support of Snowden and WikiLeaks document provider Bradley Manning. Both men have been portrayed as traitors and whistle-blowers. Manning was acquitted on July 30 on the most serious charge of aiding the enemy, but he was convicted on several other counts and likely faces a lengthy term in a military prison.

Russian lawyer Anatoly Kucherena, center, speaks with journalists at the Sheremetyevo International Airport in Moscow after meeting with Snowden on Wednesday, July 24. Kucherena said he was in daily contact with Russian authorities about securing permission for Snowden to leave the airport.

Snowden meets with human rights activists and lawyers on July 12 in a transit zone of the Russian airport. It was his first public appearance since he left Hong Kong on June 23. He announced that he was seeking refuge Russia while awaiting safe passage to Latin America, where he has been offered asylum.

Russian President Vladimir Putin attends a meeting in Prokhorovka on July 12. Russian officials said Snowden abandoned his effort to seek asylum in the country after Putin warned that he would have to stop leaking information about U.S. surveillance programs if he wanted to stay.

A woman burns American flags during a protest in support of Bolivian President Evo Morales in front of the U.S. embassy in Mexico City on July 4. Leftist Latin American leaders and activists were fuming after some European nations temporarily refused Morales' plane access to their airspace amid suspicions Snowden was aboard.

Bolivian President Evo Morales holds a news conference at the Vienna International Airport on July 3. He angrily denied any wrongdoing after his plane was diverted to Vienna and said that Bolivia is willing to give asylum to Snowden, as "fair protest" after four European countries restricted his plane from flying back from Moscow to La Paz.

Umbrellas with slogans are lined up before a protest march to the U.S. consulate in Hong Kong on June 15. Snowden was hiding in Hong Kong, where he arrived on May 20 before blowing the lid off the NSA surveillance operation.

Protesters in Hong Kong shout slogans in support of Snowden on June 13. The NSA leaker vowed to fight any bid to extradite him from Hong Kong.

Graffiti sympathetic to Snowden is stenciled on the sidewalk in San Francisco on June 11.

An American flag flutters in front of the U.S. consulate in Hong Kong on June 10.

Snowden outs himself on June 9 in the British newspaper The Guardian, which published details of his revelations about the NSA electronic surveillance programs. "I have no intention of hiding who I am because I know I have done nothing wrong," he said in a video interview.

NSA leaker Edward Snowden

Photos: NSA leaker Edward Snowden

Some did it for the money, some did it for idealism, others didn't do it at all. The United States has seen a number of high-profile leak scandals in the years, most recently involving former intelligence contractor Edward Snowden, who revealed himself as the leaker of details of U.S. government surveillance programs run by the U.S. National Security Agency to track cell phone calls and monitor the e-mail and Internet traffic of virtually all Americans. Snowden has been granted temporary asylum in Russia after initially fleeing to Hong Kong. He has been charged with three felony counts, including violations of the U.S. Espionage Act, over the leaks.

Military analyst Daniel Ellsberg leaked the 7,000-page Pentagon Papers in 1971. The top-secret documents revealed that senior American leaders, including three presidents, knew the Vietnam War was an unwinnable, tragic quagmire. Further, they showed that the government had lied to Congress and the public about the progress of the war. Ellsberg surrendered to authorities and was charged as a spy. During his trial, the court learned that President Richard Nixon's administration had embarked on a campaign to discredit Ellsberg, illegally wiretapping him and breaking into his psychiatrist's office. All charges against him were dropped. Since then he has lived a relatively quiet life as a respected author and lecturer.

Jonathan Pollard is a divisive figure in U.S.-Israel relations. The former U.S. Navy intelligence analyst was caught spying for Israel in 1985 and was sentenced in 1987 to life imprisonment. Israeli Prime Minister Benjamin Netanyahu has publicly called for President Barack Obama to release Pollard after Pollard's wife appealed to Netanyahu.

Wen Ho Lee was a scientist at the Los Alamos Laboratory in New Mexico who was charged with 59 counts of downloading classified information onto computer tapes and passing it to China. Lee eventually agreed to plead guilty to a since count of mishandling classified information after prosecutors deemed their case to be too weak. He was released after nine months in solitary confinement. Lee later received a $1.6 million in separate settlements with the government and five news agencies after he sued them, accusing the government of leaking damaging information about him to the media.

Members of the Bush administration were accused retaliating against Valerie Plame, pictured, by blowing her cover in 2003 as a U.S. intelligence operative, after her husband, former Ambassador Joe Wilson, wrote a series of New York Times op-eds questioning the basis of certain facts the administration used to make the argument to go to war in Iraq.

In 2007, Lewis "Scooter" Libby, Vice President Dick Cheney's former chief of staff, was convicted on charges related to the leak of the identity of CIA operative Valerie Plame. Libby was convicted of obstruction of justice and perjury in connection with the case. His 30-month sentence was commuted by President George W. Bush. Cheney told a special prosecutor in 2004 that he had no idea who leaked the information.

Aldrich Ames, a 31-year CIA employee, pleaded guilty to espionage charges in 1994 and was sentenced to life in prison. Ames was a CIA case worker who specialized in Soviet intelligence services and had been passing classified information to the KGB since 1985. U.S. intelligence officials believe that information passed along by Ames led to the arrest and execution of Russian officials they had recruited to spy for them.

Robert Hanssen pleaded guilty to espionage charges in 2001 in return for the government not seeking the death penalty. Hanssen began spying for the Soviet Union in 1979, three years after going to work for the FBI and prosecutors said he collected $1.4 million for the information he turned over to the Cold War enemy. In 1981, Hanssen's wife caught him with classified documents and convinced him to stop spying, but he started passing secrets to the Soviets again four years later. In 1991, he broke off relations with the KGB, but resumed his espionage career in 1999, this time with the Russian Intelligence Service. He was arrested after making a drop in a Virginia park in 2001.

John Walker ran a father and son spy ring, passing classified material to the Soviet Union from 1967 to 1985. Walker was a Navy communication specialist with financial difficulties when he walked into the Soviet Embassy and sold a piece of cyphering equipment. Navy and Defense officials said that Walker enabled the Soviet Union to unscramble military communications and pinpoint the location of U.S. submarines at all times. As part of his plea deal, prosecutors promised leniency for Walker's son Michael Walker, a former Navy seaman.

Army Pvt. Bradley Manning was convicted July 30 of stealing and disseminating 750,000 pages of classified documents and videos to WikiLeaks, and the counts against him included violations of the Espionage Act. He was found guilty of 20 of the 22 charges but acquitted of the most serious charge -- aiding the enemy. Manning was sentenced to 35 years in military prison on August 21.

Sharing secrets: U.S. intelligence leaks

Changes imposed by the President will permanently place his signature on the intelligence initiative and help define his legacy as a chief executive who promised a more open and transparent government when he entered the White House five years ago.

NSA domestic and international phone and e-mail surveillance is considered some of the most widespread intelligence gathering performed by the U.S. government.

The agency and its supporters believe data collection authority is crucial to discovering potential terrorists who haven't yet come to the attention of national security officials.

But critics say it violates privacy rights of Americans whose data is collected even though there is no suspicion that they pose a security threat.

Karen Greenberg, director of the Center on National Security at Fordham Law School in New York, believes Obama will probably err on the side of transparency in his announcement.

"This is a President who, despite his critics and despite his wanting to keep some things secret, has always wanted to be seen as a President who embraces transparency," Greenberg said.

She said Obama faces "the tenor" of the public, which seems to indicate that "there is a trend toward wanting to restrain the powers of the intelligence community."

The White House was tight-lipped when asked about the President's response to the recommendations and any proposed changes.

"I know there's a lot of speculation about what decisions he has made and, in some cases, there have been assertions of fact about decisions he's made that I know for a fact he had not yet made when those assertions of fact were made in the press," White House spokesman Jay Carney said, noting that he would not speculate on what was forthcoming.

The review panel said that when government officials consider national security risks, they should also consider risks to privacy, freedom, civil liberties, relationships and trade with other nations.

The panel also recommended new limits on spying on foreigners and foreign leaders after controversies around the disclosures of U.S. snooping on overseas leaders such as Germany's Angela Merkel.

Federal courts are divided on NSA telephone data collection. One judge in Washington ruled preliminarily in December that it was probably unconstitutional on privacy grounds. A second judge ruling in another case in New York subsequently found it lawful.

The top-secret the Foreign Intelligence Surveillance Court, which oversees the legal aspects of surveillance, earlier this month reauthorized the program for another three months.

The program is covered under Section 215 of the Patriot Act and has been authorized 36 times over the past seven years.

CNN's Matt Hoye, Evan Perez, and Bill Mears contributed to this story.