The House Intelligence Committee released a memo on Friday that was written by Republican aides based on classified documents about government surveillance of a Donald Trump campaign adviser.

The four-page document itself does not appear to allege that anyone violated federal law, but it does outline a pattern of improper conduct by a list of high-ranking FBI and Justice Department officials during the Obama administration.

Republicans will use it to justify complaints that top law enforcement agencies had an anti-Trump bias during an election year.

These were the same agencies that cleared Hillary Clinton of wrongdoing in her classified email scandal, a subject that President Trump railed about consistently as he campaigned for the White House.

Democrats complain that the memo left out important facts and 'cherry-picked' information in order to present a one-sided view of what the FBI and DOJ did to persuade a judge to grant surveillance powers.

Former FBI Director James Comey (left) and Deputy Attorney General Rod Rosenstein (right) are among the federal officials implicated in an explosive House Intelligence Committee memo that was declassified on Friday

The memo explains how federal law enforcement used unreliable information to obtain surveillance warrants against Carter Page, then a Donald Trump campaign adviser

Former British spy Christopher Steele (left) was paid $160,000 by an opposition research firm to dig up dirt from Russians about Trump; the money was part of a larger payment made through a law firm by the Democratic Party and the Hillary Clinton (right) campaign

WHAT DID THE JUSTICE DEPARTMENT DO?

A Foreign Intelligence Surveillance Act (FISA) judge granted the Justice Department a warrant to spy on Carter Page, a Trump foreign policy adviser, partially on the basis of an anti-Trump 'dossier' compiled by an opposition research group funded by Democrats.

Using a law firm as a middle-man, the Hillary Clinton campaign and the Democratic National Committee paid the firm, Fusion GPS. Fusion then paid former British spy Christopher Steele more than $160,000 to dig up Russia-related dirt on Trump.

The Republican memo concludes that Steele himself was biased, since he 'was desperate that Donald Trump not get elected and was passionate about him not being president.'

But the FBI continued using him as a confidential source anyway, even after he violated the most basic rule of working with a government intelligence service by telling a reporter what he was up to.

The warrant application also relied on a news article by a Yahoo reporter without telling the judge that leaks from Steele himself were at its center.

When the Justice Department asked the court for permission to spy on Page, it didn't disclose Steele's bias.

It also never mentioned that it was asking for a warrant based on materials that were paid for by Trump's political opponents.

WHY IS THE STEEL DOSSIER SO IMPORTANT?

FBI Deputy Director Andrew McCabe testified before the House Intelligence Committee in December 2017 that 'no surveillance warrant would have been sought .... without the Steele dossier information.'

The dossier itself was full of bombshell claims about Trump, most notably that he cavorted with prostitutes in a Moscow hotel room that the Kremlin had rigged with recording devices.

Critics say Steele uncritically used information from Russian sources determined to compromise Trump or gain leverage over him – the exact opposite of the Democratic 'collusion' narrative that suggests Trump worked hand-in-hand with Moscow.

Republican Rep. Devin Nunes, chairman of the House Intelligence Committee, was the driving force behind the controversial memo's declassification and release

WHO IN THE GOVERNMENT IS ACCUSED OF WRONGDOING?

FISA warrants have to be renewed every 90 days; then-FBI Director James Comey, later fired by President Donald Trump, signed three of them. FBI Deputy Director Andrew McCabe signed another one.

Others to sign off included then-Deputy Attorney General Sally Yates, another official fired by Trump; then-Acting Deputy Attorney General Dana Boente; and Deputy Attorney General Rod Rosenstein.

Another official implicated in the memo is then-Associate Deputy Attorney General Bruce Ohr. Ohr's wife was employed by Fusion GPS at the same time, but the FBI never told the FISA court about it.

Ohr was reassigned and is no longer in a position to impact the other major Russia investigation – one helmed by special counsel Robert Mueller.

But the fate of Rosenstein and McCabe is up in the air. Republicans on the Intelligence Committee may have given Trump a reason to fire them both.

DOES THIS CHANGE ANYTHING FOR THE MUELLER PROBE?

In a word, no. The memo doesn't say anything that suggests Mueller or his current team are engaged in anything illegal or unethical.

But the appearance of impropriety at the Justice Department, though unconnected, will give Trump supporters ammunition to claim Mueller's investigation is also suspect.

The president has consistently called the multiple investigations a collective 'witch hunt' and insisted he never colluded with Russians to tilt the 2016 election in his favor.

HOW WILL THIS AFFECT THE 'FISA' COURTS?

Judges empowered by the Foreign Intelligence Surveillance Act (FISA) grant more than 99 per cent of the warrant applications presented by the federal government.

This episode suggests that the process can be compromised by officials who are willing to hide material facts or provide courts with one-sided accounts of what they know and how they came to know it.

The flip side is that if FISA courts begin to scrutinize warrant applications more carefully, they might act too slowly in cases where there are urgent terrorism-related circumstances that require quick action.

WHAT'S NEXT?

Democrats on the House Intelligence Committee have written their own counterpoint, a memo that they say fills in important facts the Republican majority omitted.

That document is winding its way through the same process the GOP's memo went through: committee votes to allow the full House of Representatives to see it, and then to release it to the public.

If that happens, the White House will again have five days to reject a request to declassify the Democrats' version. The White House has signaled that it will treat the two versions of history equally.