Defining and satisfying the public’s legitimate interest in the private lives of American presidents has never been an easy task for serious historians or journalists. What is appropriate and germane, and what salacious and irrelevant? Increasingly, the balance has been shifting away from circumspection toward full and, at times, fulsome, disclosure.

Blame it on Monica or a more general celebrity mania, which now grips all sectors of contemporary publishing and broadcasting, but there seems to be no limit to what may be printed or said about people who are or have been in the public eye – as long as it is true, or at least sustainable in a court of law. And this latter limit usually only applies to the living.

So it is with Lance Morrow’s book length essay, “The Best Year of Their Lives: Kennedy, Johnson and Nixon in 1948” (Basic Books, 312 pages, $26), on the character and times of John F. Kennedy, Lyndon Johnson, and Richard Nixon. It’s all here – from Mr. Johnson’s use of public defecation to humiliate his staff to Mr. Kennedy’s habitual use of the phrase, “Getting any?” in greeting his pals to Mr. Nixon’s even sadder (and less relevant?) use of profanity to approximate his missing “small talk.”

It should be noted that most, if not all, of this material is recycled from previous sources; the author’s need to rehash the details only underlines the character of our own times. The intriguing “hook” for Mr. Morrow’s book is the coincident emergence of all three national political figures in 1948. Mr. Nixon was presiding over the Alger Hiss espionage case, Mr. Johnson was engaged in the fight of his life for a Senate seat, and Mr. Kennedy, reeling from the recent deaths of two beloved siblings, was preparing to run for Congress.

Mr. Morrow can be an artful writer, and the most interesting elements of the book contrast the motives and methods of the three young politicians. He gets into trouble when he resorts to facile generalization or psychobabble. He reportedly has written 150 Time cover stories, and it shows, as in this questionable meditation on the bomb:

The true end of American innocence occurred just after 8:00 a.m. local time on August 8, 1945, at Hiroshima. After that moment, America was no longer innocent – was uninnocent, had, as Robert Oppenheimer said, ‘known sin.’ The story of 1948, especially, is the story of America’s attempt to come to terms with its new moral status.

But America resisted the idea of its un-innocence, of its sinfulness. Such a notion was dangerous to the American idea itself, to American exceptionalism. … The thought of American sinfulness opened a Pandora’s Box of inadmissible speculation – raised the possibility, in fact, that America might even be capable of doing evil.

What all three of Mr. Morrow’s protagonists shared was a degree of dysfunction in their families. Enough said on the Kennedys. The Nixons were hardscrabble strivers apparently obsessed with their uncertain social status, and Mr. Morrow makes a persuasive case that this anxiety colored Mr. Nixon’s lifelong resentment of the kind of Establishment privilege personified by Messrs. Hiss and Kennedy. The Johnsons were deeply disappointed by their downward mobility, from cattle barons to penury in one generation.

Readers of Robert Caro’s multi-volume biography of Mr. Johnson will be familiar with the Texan’s enormous capacity for both personal greed and generosity. Mr. Morrow tracks this theme effectively, from Mr. Johnson’s tearful concern that he would never be able to repay his dying father’s debts to his inauguration as the richest man ever to have occupied the White House. How Mr. Johnson obtained such wealth, all the while serving in the halls of Congress, has been the subject of considerable speculation and controversy over the years.

Mr. Morrow has no room here for a bill of particulars; he simply notes that a number of firms regulated by or standing to benefit from the federal government had a habit of advertising on Lady Bird Johnson’s Austin, Texas radio station. He also mentions in passing that Mr. Johnson sought and was granted a valuable CBS affiliation for the station, while serving in an influential position in Congress. Readers of Mr. Caro’s much more detailed account of the building of the Johnson family fortune might reasonably conclude that President Johnson’s Great Society welfare program began at home.

The most interesting Johnson material concerns his high-stakes 1948 campaign against the popular former Texas Democratic governor, Coke Stevenson, for a U.S. Senate seat. The campaign introduced major corporate campaign contributions, barnstorming by helicopter and other accoutrements of the contemporary political scene. Some observers have called this the first modern political campaign.

Mr. Johnson, a formerly liberal New Dealer, sensed a rightward trend in the country and, astonishingly, decided to attack the conservative Stevenson as a pro-labor liberal. Nothing could have been further from the truth, but Mr. Stevenson broke the first rule of elective politics by failing to respond, and the lie stuck.

So much has been written and said about the Kennedys that I approach newly published material with reluctance. Yet the Kennedy sections turn out to be the best in the book. No Kennedy-hater, Mr. Morrow gives JFK the benefit of the doubt in terms of his ultimate historic significance. But he is enough of a storyteller to locate a unifying theme, and his theme here is mendacity.

The Kennedys lied about JFK’s life-threatening illnesses, about his sister’s retardation and lobotomy, about another sister’s extramarital adventures and the circumstances of her death, about Joe Kennedy’s business dealings. It was apparently a family reflex. Only the Kennedys could make a heroic story out of the PT-109 episode; others asked how the agile PT boat was hit by a destroyer in the first place. As Mr. Morrow puts it, “PT-109 asked whether Kennedy was a war hero who saved his men or a slovenly skipper whose inattention got his boat sunk and two men killed.”

The Nixon sections are less compelling. Mr. Morrow has difficulty connecting with Mr. Nixon’s admittedly elusive and enigmatic character. He makes do with a kind of opportunistic Rake’s Progress until the final denouement in the Watergate scandal. You can tell the author is straining when he draws an extended comparison between Richard Nixon and actress Lana Turner:

It is, on the face of it, a preposterous and frivolous comparison (so far, so good)…But one cannot understand Richard Nixon without help from unusual quarters. Turner and Nixon were in something of the same line of work – one a professional movie actress, and the other a career politician. A sex symbol is supposed to be sexy, but Lana Turner was, deep down, rather the reverse. A politician might be expected to be gregarious, or at least, to like people, and wish to be with them. But Nixon did not. Both Turner and Nixon were isolated, manipulative, calculating, detached.

One Morrow nugget regarding Watergate that I did not know was that Washington Post reporter Carl Bernstein, who helped break the story, was the son of a labor organizer and Communist Party member subpoenaed by Richard Nixon’s House Un-American Activities Committee. You can’t help but wonder what bloggers would have made of this connection, had bloggers been around back then. This is a disturbing book in that it portrays three recent presidents as fundamentally and seriously flawed. It even suggests that two of the three (Mr. Johnson and Mr. Nixon) were mentally ill while in office. That it does all this persuasively makes it a valuable, if unpleasant, read.

Mr. Willcox last wrote in these pages on war in the 20th century.