Arlington County, which stands to lose $5 million awarded by a jury last week to a bystander who lost both legs during a 1979 high-speed police chase into the District, apparently has the strictest policy in the metropolitan area governing "hot pursuit" by police.

That policy, instituted in 1974 by former Arlington police chief Roy C. McLaren, was a central point against Arlington and its police officer Michael Kyle brought by Alvin Biscoe, a 50-year-old official with the National Science Foundation.

Biscoe lost both his legs after a car, driven by bank robbery suspects that Kyle was chasing, pinned Biscoe against a lamppost as he was standing in a lunchtime crowd at 19th and E streets NW. The fleeing car was going about 80 miles per hour and Kyle was close behind, according to testimony during the trial.

Although local rules vary, all area jurisdictions permit police to cross state lines in pursuit of felons, though most bar interstate chases of persons suspected of minor crimes.

Only Arlington, among local jurisdictions, addresses how fast police can go in emergency situations such as "hot pursuit" chases and expressly prohibits members of its own department from chasing suspects into Maryland or the District at speeds greater than 20 miles over the posted limit. The judgment against Arlington turned, at least in part, on Biscoe's contention in court that officer Kyle was in violation of that policy at the time of the accident.

The Arlington board voted unanamously yesterday to appeal the verdict, which could mean a seven-cent increase in next year's property tax rate because the county carries no insurance against such suits. Virginia jurisdictions operate under the doctrine of sovereign immunity, which means they can't be sued in Virginia for injuries that result from county employes' performance of their jobs.

During the 15-day trial in U.S. District Court in Washington, Judge Harold H. Greene ruled that sovereign immunity did not apply in the Biscoe case because the District of Columbia does not recognize that principle. Greene's ruling and the subsequent verdict marked the first successful challenge to Virginia's soverign immunity claims.

Kyle, Arlington County (which trained and supervised Kyle) and the driver of the car that crashed into Biscoe were held equally liable for the accident. Because neither the convicted robber nor Kyle can foot the $5 million bill, Arlington would be responsible for payment.

"People say Arlington's a big county, a wealthy county," said County Board chairman Ellen M. Bozman, "but this would mean a seven-cent increase on the tax rate. If this decision stands after appeal, then we have a major public policy question: Do we tell all our employes to stop at the state line?"

Arlington officials say they are currently reviewing all police department policies, but like other area jurisdictions plan no immediate changes as a result of the verdict. County manager Larry Brown said police chief William K. (Smokey) Stover "is telling the troops we're still going to chase bank robbers and do the job we're paid to do."

Although Kyle testified he didn't know how fast he was going when the crash occurred, a police report he filed shortly after the crash stated that the fleeing car was going 80 miles an hour in a 25-mile-per-hour zone. Witnesses testified that Kyle, who had pursued the robbers across the Theodore Roosevelt Bridge and the E Street Expressway, was following close behind. The two fleeing men were convicted of stealing $3,000 in marked bills from an Arlington branch of the Washington-Lee Savings & Loan.

Biscoe's attorney Joseph H. Koonz Jr. argued that Kyle negligently caused the accident when he chased the suspects at a high speed in violation of Arlington's "hot pursuit" prohibition, which Koonz said has the force of law. Koonz claimed that Arlington was negligent because Kyle was improperly supervised.

William B. Dolan III, the Arlington attorney who represented Kyle and the county, argued that the regulation was "merely a guideline." Dolan said Kyle acted reasonably in trying to protect himself and the public "against bank robbers who would shoot police officers in a minute." There was testimony during the trial that six shots were fired at Kyle as the two cars raced through the E Street tunnel.

High-speed chases present a troublesome problem for law enforcement officials. No one knows how many people are killed after crashes with police who are chasing suspects, but a 1967 study placed the national annual figure at 500.

Last September, the police chief of Wardensville, W.Va., was exonerated by a federal jury in Alexandria of responsibility in the 1981 deaths of six people, four of them Northern Virginia teen-agers, during a high-speed chase. The police chief had chased a suspected drunk driver into Virginia, where the suspect's car collided head-on with a Volkswagen bus near Winchester.

Local police department regulations generally mirror the guidelines promulgated by the 14,000-member International Association of Chiefs of Police (IACP), which state that before officers engage in high-speed chases they must weigh "present danger, seriousness of the crime, the length of pursuit and the possibility of identifying the suspect at a later date."

Virginia state police policy specifically addresses the question of speed: "To establish a speed limit above which, or a circumstance in which, a member would not pursue a fleeing driver would constitute an invitation for crime or traffic violators to increase their speed to that particular limit."

"Hot pursuit is clearly a judgment call," said Robert Angrisani, communications director for the Gaithersburg-based IACP. "On one hand, police officers don't chase ghosts, and until we come up with some better way to bring the crime problem into controllable limits, the more proper course of action is to make the instigator of the chase responsible. But if negligence is clearly proven, then the officer should be held accountable."

"There's so many things an officer has to consider--how desperate is this person, is he likely to kill somebody, take hostages?" said Montgomery County police officer Robert Muehlenhort. "It's mind-boggling how much can go on in a short time."