A Guide to the Federal Government’s Wiretap Powers - Wall Street Journal

A Guide to the Federal Government’s Wiretap Powers
Donald Trump claims Barack Obama tapped his phones. How would that have been possible?

President Donald Trump made shocking allegations on Saturday morning that President Barack Obama tapped his phones in the Trump Tower skyscraper. His comments, offered without any proof, fanned interest in a continuing FBI investigation of ties between Mr. Trump’s allies and Russian officials.
The allegations appeared to be taken from media reports alleging the Obama administration received authorization to conduct surveillance on the Trump campaign. How would that have been possible?
Below is guide to the federal government’s power to snoop in criminal investigations and intelligence collection.
Which laws authorize the use of wiretaps in the U.S.?
The Foreign Intelligence Surveillance Act guides the use of wiretaps in service of intelligence collection, while Title III of the Omnibus Crime Control and Safe Streets Act of 1968, also known as the Wiretap Act, dictates the use of wiretaps in criminal investigations.
What’s the difference?
The purpose of intelligence is to gain information about the activities of foreign powers. The purpose of a criminal investigation is to collect evidence to support prosecution in court. Under Title III, federal prosecutors can seek a warrant to tap the phones of suspects of a range of crimes, from bribery to espionage, but only with authorization by the attorney general or other high-level Justice Department officials. They then must satisfy a federal judge that they have probable cause that a crime occurred or will occur, through the filing of applications that detail the “facts and circumstances” of alleged offenses and targets. Prosecutors must also justify the necessity of a wiretap instead of less intrusive investigative techniques.
What is FISA used for?

The Justice Department and the Federal Bureau of Investigation can obtain warrants and orders from a secret court that allows them to conduct surveillance of and collect information about suspected spies and terrorists.
Prosecutors and agents seeking a wiretap under FISA need a warrant from the Foreign Intelligence Surveillance Court to tap a phone in the U.S., with limited exceptions. To tap the phone of a foreigner living in the U.S., they have to demonstrate probable cause to believe the target is an agent of a foreign power. Any employee of a foreign government—like, say, the Russian ambassador—would qualify. But to get a warrant for a U.S. person, they must show probable cause to believe something close to espionage or other national security crimes, like terrorism, occurred, said Julian Sanchez, a senior fellow at the Cato Institute.
How could we know if Mr. Trump’s wiretaps allegations are true?
FISA orders are classified as a general rule, said Todd Hinnen, a partner at Perkins Coie LLP and former acting head of the Justice Department’s National Security Division. But nothing would stop Mr. Trump from declassifying FISA orders, he said.
“If there were such an order regarding Trump obtained by the Obama administration, for instance, President Trump could have it declassified and release it to the press,” he said.
Can FISA be used for more than just wiretaps?
Yes. Under FISA, federal agents can also seek warrants to search premises and orders for certain business records, such as which websites a target visits. Emails generally require a warrant, but the law is unsettled about whether investigators can obtain stored email without one.
Can evidence collected under FISA be used in a regular court?
Yes. The Justice Department can use FISA to gather evidence for criminal prosecution as long as foreign intelligence is a significant component of the investigation, Mr. Sanchez said. But it doesn’t have to be the primary purpose. The government has to tell the defense that it intends to use evidence collected under FISA in a criminal case, offering the defendant a chance to challenge it as unlawful or unconstitutional and try to have it suppressed by a judge.
What is FISA’s back story?
Congress established FISA to guard against surveillance abuses in the name of national security. It passed in 1978 following revelations of an FBI surveillance program that targeted anti-Vietnam War protesters and civil-rights organizers, including Martin Luther King Jr., as well as the Watergate scandal that ultimately forced President Richard Nixon’s resignation.
More recently, a George W. Bush-era program authorized the National Security Agency to wiretap communications between foreigners suspected of having links to terrorist groups and people in the U.S. without a warrant. The government halted the practices for a time, but resumed them in the Bush and Obama administrations after the law governing wiretaps was changed.
—Bob Davis contributed to this article