Maryland's highest court threw out Gov. Parris N. Glendening's legislative redistricting map yesterday and pledged to redraw the state's political boundaries, free of partisan meddling, in time for September's primary elections.

The Maryland Court of Appeals ruling said "significant portions" of the map violated the state Constitution because the circuitous boundaries of several districts cut across county lines or leapt over natural barriers and split long-standing communities.

The decision stunned Maryland's top elected officials, who were counting on the new lines to secure an even broader Democratic majority in races for the state's 188 General Assembly seats. Politicians and the attorneys who brought the case against Glendening's plan called yesterday's order astounding.

"I'm still in a state of shock," said state Sen. Norman R. Stone Jr. (D-Baltimore County), a 40-year member of the legislature whose district was shattered by the governor's map. Yesterday, his prospects for reelection were instantly revived.

"This is unprecedented. It's what should have happened," said M. Albert Figinski, a 30-year veteran of redistricting battles who is representing Stone and another senator. "It's wonderful news for people who believe in an impartial judiciary. And it's wonderful news for people who believe in the Maryland Constitution."

The governor's office issued a subdued response to the ruling, criticizing the court for failing to outline specific objections to the plan. Glendening (D) defended the map he devised with help from legislative leaders.

"Great effort was taken to ensure that each district fairly and accurately represented the interests of its citizens and caused as little disruption throughout the state as possible," Glendening said in a statement.

A separate map for congressional districts is not affected by the decision.

Redistricting maps routinely meet with court challenges in Maryland and across the country. This year, courts have thrown out legislative maps in a half-dozen states, primarily because of state constitutional concerns, said Tim Storey, a redistricting expert with the National Conference of State Legislatures.

Among the casualties: the Republican-drawn map in Virginia, where a Circuit Court judge in March nearly forced new elections for the General Assembly. The state Supreme Court stayed that ruling and is expected to review the plan this year.

In Maryland, the Court of Appeals has resisted making sweeping changes to political boundaries. The court invalidated a governor's map only once before, in 1972. During a hearing Monday, the judges indicated that they would act only reluctantly, because even small changes could require them to shift lines across the entire state.

Yesterday's order, signed by Chief Judge Robert M. Bell, asks attorneys in the case to recommend mapping experts by tomorrow to help the court devise a new plan.

The redistricting dispute already has forced the state to delay the filing deadline for state candidates by a week, to July 8, and Bell has indicated that he has no desire to further disrupt this year's elections.

But Secretary of State John T. Willis said the notion that the court could quickly whip up a new map is "naive."

"This is extraordinarily complex," he said. "We saw thousands of pages of exhibits, we reviewed a mountain of data and a forest worth of paper."

Willis warned that the court could inadvertently create problems with every change. One worry, he said, is that new lines would violate federal laws that require minorities to be adequately represented in Annapolis.

State leaders also are concerned that the court may not draw districts to maintain Democratic dominance, particularly in Republican-leaning eastern Baltimore County.

The redistricting process, a State House ritual that occurs once each decade to account for population changes revealed by the U.S. Census, began almost exactly a year ago. But the process didn't get rocky until April, when the Court of Appeals cast doubt on the plan's validity and ordered it be reviewed by a special master.

In May, Bell revealed that he and other judges had been contacted by four state senators, including longtime Senate President Thomas V. Mike Miller Jr. (D-Prince George's), who wanted to discuss the redistricting case. Last week, the Republican Party asked the court to launch criminal contempt proceedings against them and a fifth senator who wrote a letter to the special master in the case, accusing them of conspiring to corrupt the judicial process.

The court has yet to act on that request. But Republicans said yesterday that the court's decision to throw out the Democratic plan will go a long way toward restoring public faith that the court was not influenced by political pressure.

Yesterday's order revived complaints the court first voiced 10 years ago, when then-Gov. William Donald Schaefer (D) began pulling population from Baltimore County into Baltimore senatorial districts. Schaefer was trying to preserve the city's political clout in Annapolis and protect incumbents as the city lost population.

A five-member majority let the plan stand, but chastised the state for coming "perilously close" to invalidation.

This time, the state's map made even more incursions across county lines, primarily to protect Democratic incumbents.

Although Baltimore's population of 650,000 would support five city-based senators, the map sets up seats for eight. And old lines that once had Baltimore County divided up among seven senators have been replaced by borders that leave the county represented by 12 senators.

Stone said the new map had residents of his Baltimore County district represented by four different senators and 12 delegates.

"I filed this suit because I didn't want to see those communities broken up," he said.

At Monday's hearing, Bell appeared annoyed that the state had not heeded the court's 1992 warning, asking the state's lawyer: "What does perilously close to unconstitutional mean to you?"

As for Miller, the state tailored a district that includes pieces of Prince George's, Charles, Calvert and Anne Arundel counties -- the first four-county district in state history outside the rural reaches of the Eastern Shore.

Miller has repeatedly defended his plan as the best way to deal with Southern Maryland's fast-growing population.

But attorneys for Prince George's County Executive Wayne K. Curry (D) called it the most egregious constitutional violation in the state, arguing that the new district was white enough to give Miller an advantage over a black challenger in the Democratic primary, but black enough to allow Miller to survive against a Republican in the general election.

Compared with redistricting a decade ago, the new plan "pays much less respect to county borders and is even more protective of a set of favored white Democratic incumbents at the expense of the law," said Curry's attorney, Sam Hirsch. "Today, the court said: 'Enough.' "

"I'm still in a state of shock," said state Sen. Norman R. Stone Jr. (D-Baltimore County), who filed suit against the redistricting plan.