Michael K. Deaver, once one of President Reagan's closest advisers, returns to court today to face charges of lying to Congress and a federal grand jury in a trial that seems likely to revolve around Deaver's claim that he is an alcoholic.

Lawyers for the 49-year-old former White House deputy chief of staff have indicated they will argue that Deaver's dependence on alcohol and his health problems made him less likely to lie.

In papers filed in the case, the lawyers have said that Deaver's physical condition "made it more likely than not that he was telling the truth when he said he did not recall" details of the incidents cited in his five-count indictment. The former Reagan aide is charged with lying about contacts he made with senior administration officials on behalf of clients of the once-thriving lobbying company he founded after leaving the White House in 1985.

The image of Deaver, for more than 20 years a confidant of President Reagan and his wife, Nancy, as a troubled alcoholic is expected to clash during the trial with the widely held view of him as a sober, hard-working aide who knew the Reagan's moods and instincts better than anyone in Washington.

The trial is expected to last six to 11 weeks and to offer glimpses of how the Reagan White House worked and how influence and power were exercised by a member of the president's inner circle.

Deaver, whose clients and personal wealth have evaporated in the glare of fighting the case, has pleaded not guilty to all counts. If convicted, he could face a maximum sentence of 25 years in prison and a $34,000 fine.

Whitney North Seymour Jr., the prosecutor, is one of six independent counsels appointed to investigate allegations of top-level federal corruption. He has not charged Deaver with violating any lobbying laws, but he is expected to argue that Deaver's conduct was improper.

Deaver's team of lawyers, headed by Herbert J. Miller Jr., a seasoned criminal lawyer who helped defend former president Richard M. Nixon after the Watergate scandal forced him to resign, will counter that Deaver's conduct was nothing more than standard lobbying technique and hardly improper. As a result, the Deaver defense will state that Deaver had nothing to conceal or lie about.

Today's proceeding will mark the second time Deaver has entered the federal courthouse at the foot of Capitol Hill to begin trial on the charges. His first trial began July 13 and ended abruptly four days later when U.S. District Court Judge Thomas Penfield Jackson announced he could not continue the trial in the face of a U.S. Court of Appeals ruling that struck down his jury selection procedures.

The judge said he been humiliated in the eyes of potential jurors by being ordered to stop questioning individual jurors in private.

Pretrial maneuvering began long before Deaver's indictment in March. The case has twice been appealed to the Supreme Court, which has declined to halt the proceedings.

On Friday, Seymour again tangled with the Justice and State Departments and the Canadian government over their charges that he created an international incident with his second attempt to force Canadian Ambassador Allan E. Gotlieb to testify against Deaver. Gotlieb previously invoked diplomatic immunity and won a court ruling from Jackson quashing a subpoena for him to testify about Deaver's work for the Canadian government on the issue of pollution caused by acid rain.

While Gotlieb will not be called to testify, many of the Reagan administration's top officials will. During the July trial, lawyers told potential jurors that the president and Nancy Reagan were among the potential witnesses. White House officials have said it is unlikely that the Reagans will testify, but a number of top officials, including Secretary of State George P. Shultz, Transporation secretary-designate James H. Burnley IV, former Transportation secretary Elizabeth Hanford Dole, Treasury Secretary James A. Baker III, and former White House national security advisers Robert C. McFarlane and John M. Poindexter seem almost certain to be called as witnesses.

Another likely focal point is the alcoholism defense, which Jackson earlier this month ruled Deaver may use. His lawyers have said in court papers there is no precise precedent for the defense because it does not claim that alcoholism made Deaver incapable of willfully committing a crime.

Rather, it will stress that Deaver's health was so poor that he was probably telling the truth when he said to a House subcommittee and to the grand jury that he could not remember certain events mentioned in the indictment.

". . . Evidence will show that no one in Mr. Deaver's medical condition could be expected to remember much of anything about certain periods of his life, particularly those in close proximity to his hospitalizations, and that his memory of events during other periods would understandably be spotty," one pleading said.

Deaver was hospitalized three times during periods critical to the case, once for what was believed to be kidney failure and twice for alcohol detoxification, according to the defense. Since then he has become an active member of Alcoholics Anonymous and "has achieved and remained in a state of recovery," the lawyers have said.

Seymour countered in an Oct. 1 pleading that Deaver's claims of the impact of alcoholism on the truth of his testimony represent a "smoke screen" and are unsupported by scientific evidence. "While Deaver's alcoholism is a sympathy-inducing factor the court can take into account at sentencing, it is wholly inappropriate for Deaver to argue or suggest to the jury that he should be acquitted out of sympathy because he is an alcoholic."

Seymour also has indicated he will challenge Deaver's accounts of his hospitalizations, contending that Deaver has exaggerated his medical condition and that he was, in fact, in much greater control of his faculties during his hospitalization than he has conceded.