Last month, Maryland's two U.S. senators introduced a bill called S 1578. Perhaps because it had nothing to do with gasoline or SALT, perhaps because it was only five paragraphs long, it got very little attention.

But it is a bill that ought to pass before any of the others.

It would provide $600,000 to a Northwest Washington doctor named Halla Brown. She is, to say the very least, deserving.

At about 7:30 a.m. on April 20, 1974, Dr. Brown was being driven to work by her husband, Dr. Arthur Rosenbaum. They were "broadsided" at 34th and Garfield Streets NW by the cultural attache of the Panamanian embassy, Alberto Watson-Fabrega, who had just run a red light in an embassy Toyota, according to police.

Dr. Brown, a professor of medicine at George Washington University and a research allergist at the height of her career, suffered a severe injury to her spine. She has been bedridden since the accident. The only part of her body she can move is her head -- and she can't do that very well or very often.

Because of her injuries, Dr. Brown and her husband were forced to sell their home and move into an apartment with specially constructed sickbed facilities.

Dr. Brown requires 24-hour nursing care at the rate of $180 a day, not to mention the thousands of dollars her husband spent for sickroom equipment, neurologists' services and more.

The family had medical insurance to help defray Dr. Brown's bills. But the insurance never covered all of the costs -- and the bills are now about to exceed the limits for certain kinds of coverage.

Meanwhile, in the five years since the accident, Dr. Brown has lost at least $250,000 in earnings.

But because of our diplomatic immunity laws, nothing ever happened to Alberto Watson-Fabrega.

He was never arrested. He was not even given a traffic ticket, although he admitted to the police that the accident (in which he was only slightly injured) was his fault.

And most important in this case, Watson-Fabrega was never sued by Dr. Brown because diplomatic immunity prevented it. Nor could Dr. Brown have sued the Panamanian government, for the same reason.

Watson-Fabrega simply served out his time in Wasington until he was routinely reassigned in 1977. He never called or wrote Dr. Brown.

But in August, 1978, Congress rewrote American diplomatic immunity laws for the first time since 1790. The case of Halla Brown was often cited to entice opponents over to the other side.

The new immunity bill brings all but top-ranking embassy personnel under U.S. laws for the first time. But its provisions are not retroactive, so Halla Brown cannot benefit from it.

Dr. Brown's attorneys won a $20,000 settlement last year from GEICO'S uninsured motorists pool.

Meanwhile, early in 1978, under pressure from the State Department, the Panamanian government gave Brown and her husband $100,000.

Cynics noted two things about the Panamanian gift however:

First, it was four years late. Second, the Panama Canal treaty was being debated in the Senate at that time, and both Maryland senators were considered key swing votes.

But now Halla Brown finally stands to draw even, cynics or no.

Mike Klipper, an aide to Sen. Charles McC. Mathias (R-Md.), said he "can't predict" the chances of the $600,000 'Brown relief bill, although he added: "The amount of money would probably cause most of the objections, if any."

But Bill Sudow, Dr. Brown's attorney, pointed out that Dr. Brown's accumulated expenses and lost income will total $1 million within the next decade. "And in cases like this, jury awards of $2-to- $4 million are not unusual," Sudow said. "So we are optimistic."

Me, too. But in one way, the whole output of the U.S. Mint wouldn't be enough to get Halla Brown even.

When the mistakes rain, they pour . . .

Someone masquerading as me wrote in this space last week that a ride at the front of a Metro car "stunk." Of course, the impersonator meant "stank," as several District Liners pointed out. For those keeping score, that's the first past participle the impersonator has muffed in 20 years.

Meanwhile, Edward O'Brien asks the same impersonator to make clear that O'Brien was merely a user and proponent of the phonetic alphabet reported here -- not its author.

But those who were waiting for a correction on the size of Peggy Varney's gas tank will have to wait a long time.

Varney advises that she bought her 1975 Ford Granada at the end of the model year, when Detroit was affixing smaller tanks to some cars. Thus, although most 1975 Ford Granadas have 19.2 gallon tanks, Varney's holds but 12.

Hey, you can't be wrong about everything . . .