Lyndon Johnson taped as many conversations as possible so that he could document as much of his presidency as possible. He was concerned with his own legacy after stepping in as President after John F. Kennedy was assassinated.
He did, except for the portion of one tape that was "accidentally" erased.
charged him with obstructing justice
3 Days
From the revelation of the taping system in 1973 until his death, Nixon argued that his reasons for taping were historical. OR Nixon listed several reasons behind his decision to record his conversations. The primary reasons were administrative and historical, part of the president's desire to make his administration "the best chronicled in history."
Richard M. Nixon was the President implictated in the Watergate Scandal.
Certain communications with the president are confidential.
Watergate. Nixon sent in burglars into the Watergate building where the democratic headquarters was located. A security guard found them by noticing a piece of masking tape on the door jam. Nixon was able to hide his relationship with the burglars until it was discovered that his instructions had been taped in the Oval Office. Two investigative journalists were told about the taped conversations and were able to uncover the plot. Not long after in an interview with David Frost Nixon stated that the president was "above the law" and laws didn't apply to him.
Nixon was caught in a lie and cover up concerning the Watergate break in. He had tape recorders in the Oval Office and the tapes showed how involved he was in the plan and coverup. They were taped conversations between him and Dean, Colson, and others.
handing over secret tapes of oval office conversations to prosecutors
Money that was paid to the "plumbers"apprehended at the Watergate was traced to a slush fund linked to the Committee to RE Elect the President (CREEP).Subsequent investigations, spurred by ongoing coverage in the Washington Post, led to high ranking officials in the Nixon administration.Finally the revelation of the White House system for taping conversations uncovered the "smoking gun" a tape which proved that the President himself had knowledge of the cover-up.Nixon's only option, to avoid impeachment, was to resign the Presidency.
handing over secret tapes of oval office conversations to prosecutors
"It was a missing tape that proved President Nixon had prior knowledge of the Watergate Office breakin." This previous answer is not correct. The 'smoking gun' refers to a known tape of Nixon discussing paying Hunt/Liddy (2 of the people involved in watergate) money. It is called The "Smoking Gun" tape because it shows that Nixon was willing to pay money to keep them quiet which is considered by many to be a strong indication that Nixon had a great deal of involvement within the scandal. It does not directly show Nixon as being in an central role however it proves he had knowledge and involvement. It is believed however that Nixon did not authorise the Watergate break in, however he did set up circumstances which could allow it to occur. The missing tape is actually an 18.5 minute section which is missing from a complete tape, this was later claimed to be accidentally deleted while transcripting. It is not known what this tape contained, however it is widely believed to contain Nixon discussing how he intended to use the CIA/FBI to hush up the incident.