It was every defendant for himself today as attorneys representing codefendants of Maryland Gov. Marvin Mandel tried to separate their clients from each other in the minds of jurors.

"You will hear days of testimony when the name of Irvin Kovens isn't even mentioned," said Norman Ramsey, attorney for Kovens.

"In the drama that unfolds . . . my client appears for a very few short scenes and that's it," said Charles G. Bernstein, public defender for Ernest N. Cory, Jr.

"You will become convinced after the first few weeks that this trial is not about William Rodgers," said William Rodgers' lawyer.

Even brothers broke from each other in opening defense statements today. William Rodgers, through his attorney, claimed that he was only following the wishes of his younger brother and codefendant Harry W. Rodgers when he kept secret his ownership of the Marlboro Race Track.

Michael Marr. Attorney for William Rodgers, said that his client argued for public disclosure of their purchase but bowed to "his brother's sensitivity about seeing his name splashed across the newspapers."

Purchase of the now-defunct track and subsequent official actions regulating the state's racing industry are the focal point of the government's case against Mandel, the Rodgers brothers, millionaire Irvin Kovens, Tidewater Insurance executive W. Dale Hess and Laurel attorney Ernest N. Cory, Jr.

In a multicount indictment, federal prosecutors charged these men with constructing an elaborate web of deceit and corruption by passing on thousands of dollars of gifts to Mandel who, in return, allegedly influenced legislation that benefited the businesses of his five codefendants, especially the Marlboro Race Track.

Today in opening statements, the defendants tried to cut the threads of the prosecutor's web by claiming that they knew nothing of the others' actions or, as in William Rodgers' case, disagreed with those actions.

It is crucial, all four attorneys said, that the evidence against one defendant does not "tar" the others with guilt by association.

The attorney for the younger Rodgers brother Harry led off the morning's statements by claiming that the case of Harry Rodgers "stands and falls on friendship."

Because of Harry's friendship with the governor, said attorney Thomas C. Green, "Harry Rodgers came to be in the press more and more . . . after a whirl of publicity like that it was beginning to wear thin."

So Harry "deliberately" hid his ownership in Marlboro from the press andMandel to save the governor from political embarrassment and deep his own name out of the newspapers.

Friendship, said Green, was also the primary motivation for the gifts Harry Rodgers gave to Mandel. The Florida vacation trip, suits and extension of credit to the governor were signs of generosity "with no strings attached."

"And Marvin Mandel is not the only friend Harry Rodgers has helped," said Green.

Yesterday, Mandel's attorney set the tome for a clear separation of the six defendants, a departure from defense strategy at the last trial, which was declared a mistrial in December because the jury heard publicized accounts of two outside attempts to tamper with the verdict.

Unlike the last trial when he presented the opening statement for all but one of the dependants, Arnold M. Weiner yesterday told the jury that "I represent only Marvin Mandel and I am speaking to you only for Marvin Mandel on his befalf."

Marr, attorney for William Rodgers, tried to separate his client from W. Dale Hess, whose role in the case was most publicized, by claiming that William Rodgers initially objected to Hess as a business partner in Tidewater Insurance because "he didn't want to give up any percentages." The Rodgers brothers and Hess ran the firm together.

Marr said that William Rodgers' friendship with Mandel was distant and based on their wives' friendship, which was as "natural as motherhood and apple pie."

Ramsey flatly denied the crucial charge of the federal prosecutors - that Kovens secretly owned the largest shear in the Marlboro Race Track, which benefited greatly from Mandel's alleged lobbying efforts.

After dismissing that charge, Ramsey claimed his client was "not involved" in the gifts Mandel received in the prosecution's list of a "stream of benefits" save two items: $155,000 worth of tax-free bonds Kovens provided for Mandel's former wife in 1974 and suits for the governor purchased by Kovens in 1969 and charged as guard uniforms.

Because these two gifts were separated by six years Ramsey said it was an "exercise in gigantic illogic" to imagine the favors were bribes to make the governor influence legislation in 1972.

For Cory, who figures in the prosecution case as the attorney who allegedly "doctored and falsified" letters to hide ownership in the track, public defender Bernstein chose obscurity as his defense, emphasizing that Cory is unknown compared to the others.

Bernstein tried to tell the jury how Cory has gone broke because of the charges but chief federal prosecutor Barnet D. Skolnik successfully objected.

What Cory did in concealing the true owners of these investments was "honest and accepted legal practice . . . totally above board," claimed Bernstein.

While the government chose to describe Cory as a front-man for Hess, the Rodgers brothers and Kovens, Bernstein said he was a "nominee," a acting on behalf of others.

"Front man' sounds like a dimestore ganster novel," explained Bernstein, an improper suggestion, he claimed, for his client who "did nothing wrong."