Attorneys for the conservative legal group Judicial Watch told the Maryland Court of Appeals yesterday that the grand jury investigation into whether Linda R. Tripp broke Maryland wiretapping laws by recording phone conversations with Monica S. Lewinsky is politically motivated and portions of it should be opened to the public.

Judicial Watch is trying to get the state's highest court to make Maryland State Prosecutor Stephen Montanarelli comply with an order by Baltimore County Circuit Court Judge John F. Fader II that he turn over to the group an index of documents and witnesses in connection with the ongoing grand jury investigation of Tripp's actions.

The group maintains that the materials would show that the White House and Democratic Party pressured Montanarelli to pursue the case to intimidate Tripp and stymie investigations of the Clinton administration.

Deputy Attorney General Carmen Shepard, who represented Montanarelli, told the seven-judge panel that allegations of political involvement are baseless and that the secrecy of grand jury proceedings is essential to conducting effective investigations while, at the same time, protecting the rights of those investigated.

Montanarelli declined to comment.

The Court of Appeals is not expected to issue a decision on Judicial Watch's request for two to three months.

The Howard County grand jury investigating Tripp is to meet again June 18 in Ellicott City. The investigation, now nearly a year old, has encountered numerous setbacks. A conviction for violating the state law carries a maximum penalty of five years in prison and a $10,000 fine.

Tripp told a federal grand jury that she knew she was breaking Maryland law when she made some of the tapes, but her testimony was given under a grant of immunity, making it off limits to Montanarelli. Much of the state grand jury's recent effort has centered on obtaining a verifiable copy of one of the tapes, but Montanarelli has been thwarted.

Larry Klayman, head of Judicial Watch, told the court yesterday that he believes that high-level White House officials, including first lady Hillary Rodham Clinton, sent Montanarelli letters urging him to investigate Tripp. "What we're looking for is that push that came from the White House and the Democratic Party," he said.

Klayman said yesterday that Montanarelli's investigation also is designed to frighten Tripp away from helping him in a separate lawsuit he has filed against the White House over alleged misuse of FBI files.

Judicial Watch, based in Washington, was founded in 1994 and is funded mostly by Klayman and conservative billionaire Richard Mellon Scaife. It has sued the Clinton administration more than 20 times.

Anthony J. Zaccagnini, who was Tripp's lead attorney until a month ago, said yesterday that he doubts there is merit to Judicial Watch's argument. "My impression was that we had no evidence that pressure on the prosecutor from the White House was occurring," he said.

Joseph Murtha, now representing Tripp, agreed: "Do I believe Mr. Montanarelli is the handmaiden of President Clinton? I have no evidence that shows that."

CAPTION: Linda R. Tripp may have violated Maryland wiretapping laws.