President Donald Trump's hint that he has a tape of his dinner with former FBI director James Comey sounds extraordinary – but it could be completely true.

No law stops the president from recording every aspect of life in his White House. And there is no a law that blocks these recordings from being released by the president.

Secret tapes, of course, brought down President Richard Nixon. Many believed that his downfall would have stopped presidents making recordings.

That wasn't the case, at least for President Bill Clinton.

Scroll down for video

President Donald Trump implied Friday morning there might be secret recordings of conversation he had with former FBI Director James Comey. At least seven other presidents have been proven to have recorded meetings and phone calls while in office

President Bill Clinton recorded conversations in office, but he has not yet released the tapes. President George W. Bush enacted the Presidential Records Act which means any recordings made in office must be preserved for historical purposes

Because of former U.S. Solicitor General Kenneth Starr's inquiry, it was established that Clinton recorded many calls to foreign leaders and conversations he had with an historian.

However, he's keeping these tapes a secret. Whether George H.W. Bush, George W. Bush and Barack Obama made recordings is still unknown, but it is likely.

The law surrounding the recordings is actually very simple: Washington D.C. is a 'one party recording' jurisdiction; as long as one party consents to the recording, the tape can be made and the other party need not even know they have been recorded.

This means it is perfectly legal to use hidden recording devices and offer no notification that a recording is being made to dinner guests.

There is not a law that stops a president from recording meetings and phone calls in the Oval Office. In Washington D.C., it is legal to record a conversation without the other party's consent

While Nixon's notorious recordings were kept on tape, modern technology would mean that what Trump called 'tapes' would now be computer files.

Once the 'tape' has been made, it is subject both to the Freedom of Information Act (FOIA), which means that the public can ask to hear it.

Even after the president leaves office, the file would still have to exist because of Presidential Records Act. The act requires the recordings be preserved for historical purposes.

The PRA was brought in after outrage over Nixon's Watergate scandal. It says that 'presidential records' are documentary materials created by the president.

It says 'in the course of conducting activities which relate to or have an effect upon the carrying out of the constitutional, statutory, or other official or ceremonial duties of the President' must be held for public inspection in the future.

They are usually held by the president's library but it is the responsibility of the National Archives and Records Administration (NARA) to make sure that they can be accessed by the public.

While former President Bill Clinton is known to have recorded conversations in the White House, it is not proven if former President George W. Bush and George H.W. Bush have tapes

The existence or non-existence of secret recordings by President Obama. Presidents have a five-year pass before they have to respond to FOIA requests

But actually accessing a recording is not that simple.

The only presidential recordings published under the FOIA so far were those of Reagan's 'situation room' tapes. They were first requested by historian William Doyle in 1996 and he published a book containing them in 2014.

The FOIA rules have also failed to bring recordings made by Bill Clinton to light.

He held lengthy conversations with the historian Taylor Branch, who was specifically asked to make an oral history of the Clinton presidency.

In 2009 the conservative freedom of information campaigners Judicial Watch made a FOIA request to the Clinton Presidential Library for the tapes, but it said that the records were Bill Clinton's own, not public material.

That was upheld by the NARA, although Judicial Watch began litigating an appeal in 2010. The case remains unresolved.

Clinton's successor George W. Bush wrote his own rules in 2014 on how his records should be treated.

According to Politico if there are tapes, they would be released under FOIA as his guidelines for access were praised as liberal by historians.

It is unclear if any exist however; as yet no relevant FOIA appears to have been made. If they have been made, they have still to be responded to in the public domain.

As for Obama's potential tapes, their very existence or non-existence is secret, because presidents have a five-year pass on having to respond to FOIA requests before they leave office.

Presidential recordings of course have played a part in history before - notoriously so in the case of Richard Nixon.

President Richard Nixon resigned after the released of the 'smoking gun' tape before he could be impeached for the Watergate scandal

He resigned before he could be impeached after the infamous Nixon White House tapes that were made public before the Senate Watergate Committee.

Nixon ordered the Secret Service to install recording devices in the White House and taped 2,636 hours of phone calls and conversations between 1971 and 1973.

He was paranoid about how he was viewed by members of Congress and the executive branch. The 37th president was also concerned about how he was being portrayed to the media.

Most people did not know they were being taped and only a few members of the White House administration knew the sound activated recording devices existed.

Nixon's downfall spiraled because of the tapes which were exposed during the Watergate investigation into the DNC burglary while he was running for re-election.

The burglars were trying to bug the DNC headquarters at the Watergate complex.

During the investigation, the 'smoking-gun' tape led to Nixon's resignation. It proved the president ordered a cover-up of the burglary of the DNC.

President Nixon ordered the firing of special prosecutor Archibald Cox (pictured) who was investigating the break-in at the DNC headquarters at the Watergate complex

The recording revealed Nixon ordering the FBI and CIA to abandon its investigation of the break-in.

Before the release of the 'smoking gun' tape, Nixon ordered the firing of special prosecutor Archibald Cox - who was investigating the Watergate scandal - in the Saturday Night Massacre, which itself has drawn comparisons to the firing of Comey.

Nixon was pardoned by his successor, Gerald Ford, but many of his aides served time in federal prison.

Nixon wasn't the first president to secretly record Oval Office conversations. President Franklin Delano Roosevelt also recorded discussions in the Oval Office with a microphone hidden under his desk.

President Eisenhower (pictured with Vice President Nixon) used a recording device hidden in a fake telephone . However, he often forgot to turn it on before meetings

He began using the device after the New York Times published what he claimed to be a fictitious article. FDR was advised by his stenographer to record meetings to keep this from happening again.

He recorded eight hours of conversations in the Oval and stopped using it after he was re-elected in 1944.

President Dwight D. Eisenhower also used a secret recording device disguised as a telephone on his desk in the Oval Office. FDR could only tape 10 minutes at a time with his recorder, but Eisenhower was able to record a full 15 minutes.

However, Eisenhower would occasionally forget to turn the machine on at the beginning of meetings and the quality of many recordings was extremely poor. He used the device to document 75 different conversations beginning in 1953.

JFK upped the number of devices in the White House from previous administrations. Recorders were hidden in the drapes of the Cabinet Room, his study and in the Oval

President Johnson used secret recording devices as vice president and president

President John F. Kennedy had a system installed in 1962 by the White House Communications Agency. He hid microphones in the drapes of the Cabinet Room and under a coffee table and his desk in the Oval.

Kennedy had a Dictaphone machine hooked up to a telephone and taped 265 hours of meetings and 12 hours of phone calls.

His Vice President Lyndon B. Johnson also used a device and as president he used it to record 800 hours covering 9,000 telephone conversations.

Again, the quality of the Dictaphone recordings were often lacking. The tapes would often pick up background noise and JFK's leg tapping more than the actual conversation.

President Ronald Reagan also taped dozens of calls made from the Situation Room.

The recordings reveal the conversations he had with world leaders such as former Israeli Prime Minister Menachem Begin, former Syrian President Hafez el-Assad and former British Prime Minister Margaret Thatcher.