U.S. Attorney Stanley S. Harris asked a federal judge yesterday to reconsider his decision to allow jurors in the case of John W. Hinckley Jr., accused of the attempted assassination of President Reagan, to return to their homes each day after trial instead of sequestering them in a hotel.

Citing the "extraordinary publicity" that has already surrounded the Hinckley case, Harris said in court papers that sequestration is the only sure means to shield the jurors from outside influences that could affect a decision in the case. Trial is scheduled to begin Tuesday.

Harris said that otherwise, instead of having the case decided by the evidence heard in court, it "would actually be decided by the people . . . whose comments, remarks and opinions will be taken into account by the nonsequestered jurors."

In another development, it was disclosed yesterday that, attorneys for the actress Jodie Foster asked Judge Barrington D. Parker to deny a request from network broadcasters that they have access to Foster's videotaped testimony if it is played during the trial. Law enforcement officials believe that Hinckley was infatuated with Foster and tried to assassinate Reagan to gain her attention.

Further hearings on these and other procedural questions are set for Monday.

While the lawyers spar over these and other legal questions, courthouse officials scramble to prepare for the opening of the biggest legal spectacle here since the Watergate trials.

Marshals have installed extensive security measures and renovated a basement cell where Hinckley may be held, while clerks have parceled out seats in the courtroom--leaving 25 for members of the public--and installed a microwave dish atop the building so broadcast reporters can transmit their accounts of the proceedings.

Seats in Courtroom 19, where Parker will preside over Hinckley's trial, are already at a premium. Court officials have designated 50 of the 95 seats for the media, including reporters and sketch artists, and 20 others have been reserved for prosecution and defense staff and courthouse personnel.

That leaves 25 seats for the general public, and those spots will be allocated on a first-come, first-served basis on each day of the trial, court officials said. Any person who wants to enter the courtroom, including members of the public, must have an identification card with a photograph on it, such as a driver's license.

Officials are expecting that spectators will line up outside the courthouse early in the morning. The court day customarily begins between 9 and 9:30 a.m. Each person entering the courtroom will have to pass through two security checks. If a spectator leaves, he will lose his seat to the next person in line.

"If you leave, that's it," said U.S. Marshal J. Jerome Bullock, who is supervising security plans in the courthouse.

The extraordinary nature of Hinckley's alleged crime--an attempt to kill the president of the United States--has intensified security precautions surrounding his trial. And while preparations for Hinckley's security are made, law enforcement officials have not forgotten that Lee Harvey Oswald, the accused assassin of President John F. Kennedy in 1963, was gunned down in the Dallas police headquarters before he could come to trial.

"I just have a tremendous concern that no harm come to John Hinckley," Bullock said.

Bullock has declined to provide any specific information about the security operation, but he said in an interview that security for Hinckley's trial will be "more extensive" than the unprecedented precautions during the first Letelier trial in early 1979.

During that case both the prosecutor and Judge Barrington Parker, who will also preside at Hinckley's trial, were threatened. Each day, trained German shepherd dogs sniffed around the court building for bombs (none were found), and visitors to the courtroom had to pass through two metal detectors to gain admittance.

As part of the security for this trial, the entire courthouse will be cleared of everyone except judge's personal staff and closed between 9 p.m. and 7 a.m. daily, beginning Monday.

The marshals service expects to spend $7,575 a week to staff the courthouse with deputy marshals during the trial, which could take a month to complete. The D.C. police, the FBI, the U.S. Secret Service and the Federal Protective Service, which provides security on a daily basis at the courthouse with the marshals service, are also participating in the security operation, Bullock said.

Over the last few months, some changes have been made in a cell at the courthouse used for Hinckley, who has twice tried to commit suicide while he has been in custody. Enclosed lighting with impact resistant lenses has been installed, a new lock has been installed and wire mesh has been welded to the cell bars to prevent tampering with the lock. During one suicide attempt, Hinckley jammed the lock in the cell in which he was being held at Fort Meade, Md.

The cell in the courthouse is equipped with a cot and an alarm system, and it is located near an office so that Hinckley can be under constant observation. An inspector from the marshals service will be seated outside the cell when Hinckley is confined there. Bullock said Hinckley will be held overnight there at some points during the trial.