Attorneys for Maryland Gov. Marvin Mandel, who was convicted of federal mail fraud and racketering charges here three weeks ago, filed legal papers today asking the presiding judge in the case to declare Mandel innocent of the charges.

Declaring that "the (prosecutors) wholly failed to prove any violation by" Mandel, the attorneys charged that "the . . . case amounted to an attempt impermissibly to regulate the conduct of the governor."

At the same time, the governor's attorney's filed a request for a new trial for Mandel, saying that presiding Judge Robert L. Taylor had coerced the jury into returning its guilty verdict.

When the jury announced it was deadlocked after five days of deliberations, Judge Taylor should not have reminded the jurors that the case "involved much time and expense," attorney Arnoid Weiner and two associates claimed.

Also, the attorneys said, Taylor made a mistake in permitting deliberations to continue for 12 days - "an unreasonable length of time" - the motion said. During the course of the deliberations, the attorneys argued, "time itself became an impermissibly coercive forece."

At the same time as Mandel's motions were filed, four of his five codefendants also filed motions requesting that they be declared innocent. William Hundley, the attorney for codefendant W. Dale Hess, said last night that he intends to file a similar motion.

Mandel and his five codefendants - Hess, Irvin, Kovens, Harry W. Rodgers III, his brother William A. Rodgers, and Ernest N. Cory Jr. - were convicted Aug. 23 of at least 17 counts each of mail fraud and one of racketeering.

The prosecutors had alleged that Mandel accepted more than $350,000 worth of gifts, vacations and bogus legal fees from his codefendants in return for aiding legislation financially beneficial to a racetrack owned by four of the codefendants.

Codefendant Irvin Kovens has consistently maintained that he had nothing to do with Marlboro racetrack and owned no part of it. His attorney, Norman P. Ramsey, cited this contention in his request for a directed verdict of acquittal, saying that prosecutors had presented "no evidence sufficient to support a finding that . . . Kovens held (an) interest in Marlboro Race Track . . ."

Attorney Ramsey also argued that the testimony in the trial relating to the financial help Kovens gave Mandel during Mandel's divorce from his first wife, Barbara, was "irrelevant to the charges contained against him in the indictment and . . . highly prejudicial to him."

The motions filed by Mandel Kovens and the other three defendants reflect the same arguments that they made at various points during the trial and indicate the likely thrust of their probable appeals of the verdict.

In requesting a new trial for Harry Rodgers, attorney Thomas Green argued that during the course of the trial "the government relied almost entirely on hearsay, and occasionally double hearsay" from witnesses - an objection that the defense raised at times during the trial.

William Rodgers' attorney, Michael E. Marr, requested the court's premission to talk to jurors to determine whether the guilty verdict against Rodgers was reached fairly and impartially.

The question of the fairness of the jury's deliberations also was raised in Mandel's motions, with attorney Weiner noting that one juror had told a Baltimore radio station after the verdict that he wanted to vote for acquittal but "there were the other pressures to consider . . ."

The pressures juror Thomas Franz described in the interview were "the pressures of the court . . . emphasizing that no one wants a hung jury and the tremendous expense that was required."

In his other motion, Weiner said that the prosecutors were trying "impermissibly" to regulate the governor's conduct by forcing him to work "in accordance with . . . duties . . . claimed to be derived from . . . the mail fraud status but contrary . . . to the duties conferred on the governor by the Constitution of Maryland."