Mr Ehrlichman was one of the key figures in an impeachment saga very different from the one that has transfixed Washington for the past year. He served as domestic policy adviser in the White House from 1969 until 1973.
President Nixon ordered a series of burglaries and break-ins to discredit his domestic political opponents, and Ehrlichman was a pivotal figure in carrying out his instructions. He played a key role in covering up a break-in at the headquarters of the Democratic National Committee in the Watergate complex in Washington DC on 17 June 1972, the event that gave the scandal its name. The burglars wanted to replace a bugging device they had planted earlier, but they were caught. The break-in, carried out by former CIA employees and masterminded by the "Plumbers Unit" in the White House, came to light and precipitated the chain of events that would bring down the President.
Ehrlichman resigned in 1973, as Mr Nixon tried to save his own skin by getting rid of aides. But the President resigned the next year, after the House Judiciary Committee recommended his impeachment.
Mr Ehrlichman was convicted for conspiracy, obstruction of justice and perjury in connection with the Watergate break-in, for conspiring to violate the civil rights of a Pentagon official's psychiatrist, and for lying to grand juries and the Federal Bureau of Investigation. He served 18 months in a minimum-security prison camp in Arizona.
After his release, Mr Ehrlichman became a writer, then returned to corporate life.