A career woman believes her employer is guilty of sex discrimination. She is a resident of the Virginia suburbs, works in a large Fairfax County office building, and hires an Alexandria lawyer to handle her case. When it is time to go to court, her lawyer shuns the federal courthouse two blocks from his office and travels across the Potomac River to file her lawsuit in the District of Columbia.

Why?

John Grad, the lawyer who brought the suit last summer on behalf of a CIA analyst who works in McLean, reels off textbook jurisdictional arguments about federal employment disputes similar to his case.

What Grad will not discuss is what others say is an open secret among savvy lawyers in Washington's Virginia suburbs: Don't go after defense or intelligence agencies in Virginia's conservative courts if you can avoid it.

In fact, many lawyers say it's not wise to oppose the federal government on many legal issues south of the Potomac. These lawyers accuse federal prosecutors of shunting many Washington cases across the river to the federal courts in Alexandria in search of a more conservative style of justice.

"It's a different world in Virginia," says one federal law officer in the District, who agreed to talk if his identity was withheld. "The FBI and the Drug Enforcement Administration won't tell you, but it sending cases to Alexandria is there."

"It's absolutely true," says Philip Hirschkop, a veteran Alexandria lawyer who believes "the geographical accident of the Potomac River" can add several years to a prison sentence in a federal drug case brought in Virginia.

Virginia juries, drawn from the mostly white, upper-income suburbs, plus strict-constructionist Southern judges and a conservative federal appeals court in Richmond, generally make the state an ideal -- and convenient -- forum for criminal prosecutions, according to many lawyers.

But a short drive across the Potomac, they add, are less affluent jurors, a larger, more cumbersome court system and an ideologically split U.S. Court of Appeals, all of which can help tip the scales of justice in the opposite direction.

Perhaps nowhere else in the country, say federal agents, prosecutors and defense attorneys, are such stark contrasts in legal philosophies and attitudes found in such close proximity as in Alexandria and Washington.

The result is to make this area arguably the nation's capital of judge-and-jury shopping.

"I've never seen in any other jurisdiction these tenuous ties exploited the way they are in eastern Virginia," says Michael Kennedy, a New York lawyer. He said he encountered one such tie three years ago when an Alexandria drug-smuggling case he was handling featured days of testimony about the ring's activities in other states "and only a few minutes about Dulles" International Airport.

The case, he said, involved allegations against a $52 million drug ring and virtually all of the allegations involved activities in Massachusetts, Georgia and Florida. Kennedy claims the case wound up in Virginia after Drug Enforcement Administration agents forwarded a shipment of the ring's marijuana -- with sand substituted for the drugs -- from New York to Dulles International Airport.

While federal law enforcement officials generally deny or decline to comment on allegations that they try to steer certain cases into Virginia, one assistant prosecutor concedes: "You can fool around some with your jurisdictions."

"Very definitely, the best sentences are handed down in Virginia," says David Canaday, special agent in charge of the DEA's Washington district office. He adds, however, that in the majority of undercover drug investigations, his agents follow the probe where it takes them and have little control over the jurisdiction of arrests.

Some legal observers are critical of federal statutes governing alleged interstate offenses, which they say give prosecutors leeway to bring charges in any one of a number of jurisdictions, regardless of how much of the alleged crime occurred in that community.

"The defendant can't shop for a judge , only the government," says University of Virginia law professor Stephen Saltzburg. "The government gets a big advantage. And some judges don't like the look of it -- being known as a government judge."

The problem with judge-shopping, in Saltzburg's view, is that "the more widely it occurs, the less people believe justice depends on the merits of the case. It becomes a government of men and women, not laws."

William Cummings, former U.S. attorney in Alexandria, disagrees and defends the government's freedom of choice as a useful law enforcement tool. Cummings says, "Suburban juries see the city encroaching on them. They're much more likely to convict."

Two bills designed to expand the rights of defendants to choose the venue, or location, of their trial were killed in Congress last year in the face of stiff opposition by the U.S. Judicial Conference, the national organization of federal judges.

That type of measure might well have altered the venue, if not the outcome, of the widely publicized 1978 spy trial of U.S. Information Agency employe Ronald Humphrey and Vietnamese expatriate David Truong in Alexandria.

"If there was any harm to the governmental interest, it was when the documents allegedly were taken by Humphrey from the USIA in the District," says Washington attorney Michael Tigar, who represented Truong, "or when Humphrey turned them over to Truong, which was indisputably in D.C."

Today, Tigar still accuses the United States of "transparently" establishing jurisdiction across the Potomac by arranging a meeting in suburban Virginia between a government agent and Truong, who had to borrow a car to get there. The Justice Department declines to discuss the issue, noting that appeals in the case now are before the Supreme Court.

"We argued the prosecutors had the prosecutorial choice to make and the judge District Judge Albert V. Bryan Jr. of Alexandria ruled it was proper," says Justice spokesman John Russell. "We thought it was in the best interests of justice."

Tigar contends that the Justice Department was eager to try the case in Virginia because the U.S. Circuit Court of Appeals for the District had issued an earlier ruling questioning the validity of warrantless government wiretaps, which were an issue in the Truong-Humphrey trial.

The decision apparently paid off. The 4th U.S. Court of Appeals judges in Richmond, widely regarded as far more conservative than some of their brethren in the District, upheld the convictions of both men.

Meanwhile, courthouse regulars in Alexandria say that another federal judge in Alexandria, Oren R. Lewis, recently captured the flavor of judicial temperament south of the Potomac during a bond reduction hearing for three accused heroin smugglers.

Having failed to win lower bonds, defense attorney Albert Ahern asked Lewis to move the defendants from the D.C. jail to Fairfax County.

"Your honor, the D.C. jail is impossible. You should see it," said Ahern.

"I rarely go north of the Potomac, Mr. Ahern," replied Lewis, denying the request for a transfer. "I prefer it on this side."