Linda R. Tripp understood that she could be prosecuted in Maryland on charges of illegally taping phone calls with Monica S. Lewinsky, but federal prosecutors told her that the immunity protection they were providing would make it "extraordinarily difficult" for her to be convicted, a lawyer with former independent counsel Kenneth W. Starr testified yesterday.

In a hearing that could determine whether Tripp will be tried on state wiretapping charges, federal prosecutor Stephen Binhak told a Howard County judge that Starr's lawyers persuaded Tripp to hand over the tapes only after assuring her that state prosecutors could not later use the recordings against her.

Without the tapes, Binhak testified, he believed a conviction on Maryland wiretapping charges would be "extraordinarily difficult if not impossible."

When Tripp actually received immunity became the central issue in the four-hour hearing, during which Tripp's attorneys asked Howard County Circuit Judge Diane Leasure to throw out the two charges.

Tripp's attorneys argued that the charges should be dismissed because Tripp revealed the taped calls to Starr's lawyers only after she believed she had full immunity and after Starr's office subpoenaed the tapes.

State prosecutors argued that Tripp's immunity did not take effect until a judge approved it, one month after Tripp's attorneys say she signed a written immunity agreement with Starr's office. They also argued that Tripp gave one of the tapes to Starr's lawyers four days before it was subpoenaed.

Leasure said she would rule this morning on whether Tripp's tape recordings, which formed the basis for President Clinton's impeachment, were covered under the immunity agreement.

There is no clear precedent in Maryland case law that would apply to Tripp's case. Her attorney Joseph Murtha told Leasure that her ruling would be groundbreaking and that either side would likely appeal. One of the tape recordings in question is considered the key evidence in the state's case against Tripp.

State Prosecutor Stephen Montanarelli said immediately after the hearing that if the judge rules that Tripp's recordings were protected, state prosecutors would have "a problem" and would consider whether to withdraw the charges.

However, several hours later, one of Montanarelli's aides said state prosecutors had determined that they likely will proceed with the case even if they lose on the immunity issue.

"I think we'll still go forward," said Steven Halpert, one of Montanarelli's investigators. "Certainly that's how we're preparing right now."

State prosecutors called on one of Starr's deputies, Jackie Bennett Jr., to testify about Tripp's knowledge that she could be prosecuted in Maryland.

Instead, Bennett testified that Howard County State's Attorney Marna McLendon (R) had told him several days after news of the tapes became public that she felt "unbearable" political pressure to prosecute Tripp but also believed that the immunity agreement would make that "difficult."

McLendon was not called as a state witness to rebut that testimony, though she later told reporters that she never discussed immunity with Starr's lawyers. She called Bennett's testimony an "absolute mischaracterization" of their conversation.

"We never discussed the effect of federal immunity on a state prosecutor," McLendon said, pointing to two pages of handwritten notes she said she took at the time. "If there was any discussion of immunity or the likelihood of prosecution, I would have remembered it. I would have written it down."

Under Maryland's wiretapping law, both parties must be made aware that a conversation is being recorded. Lewinsky's lawyers have said she didn't know that Tripp had connected a tape recorder to the phone in her Columbia home when Lewinsky called to discuss her relationship with the president.

Tripp was indicted in July on two charges: illegally recording a Dec. 22, 1997, phone conversation with Lewinsky and illegally disclosing its contents to Newsweek magazine. Each charge carries a maximum of five years in prison and a $10,000 fine.

Tripp, who has kept a low profile during the case, waived her appearance at yesterday's hearing, which drew more than 30 reporters and photographers to the normally quiet suburban courthouse overlooking historic Ellicott City.

If Leasure rules that Tripp's tapes were not protected, Tripp's attorneys said they will argue that most of the other evidence in the case should be excluded because it is based on information she provided after receiving immunity.

Deputy Maryland Attorney General Carmen M. Shepard, whose office is assisting Montanarelli in the case, argued that state prosecutors never granted Tripp immunity.

But Bennett testified that McLendon didn't seem ready to pursue the matter.

"There was not an agreement per se" that Tripp would not be prosecuted on state wiretapping charges, Bennett testified. However, he said he told McLendon that his office "had immunized" Tripp, and that McLendon then "acknowleged that it would be difficult" to prosecute Tripp on state charges.

McLendon later turned the Tripp case over to Montanarelli, whose office acts as a nonpartisan legal watchdog.

Binhak said Tripp raised the issue of immunity from the minute he and other Starr lawyers sat down in her living room near midnight Jan. 12, 1998, the day Tripp called Starr's office to say she was being pressured to commit perjury.

Binhak said he and other federal prosecutors explained to Tripp that their immunity agreement did not guarantee that she would not be charged with breaking Maryland's wiretapping law. However, Binhak said, he told her Starr's office "would do everything we could to make sure the State of Maryland couldn't prosecute her" successfully.

"I wanted to be 100 percent sure in my mind," Binhak said, "that she knew exactly what she was getting."

CAPTION: Edward Page, left, and Paul Rosenzweig, of the independent counsel's office, leave the hearing on Linda Tripp's wiretap case.

CAPTION: Tripp faces state charges.

CAPTION: Joseph Murtha, defense atorney for Linda Tripp, arrives at the Howard County courthouse for the hearing.