When is a lawyer like a bar of soap?

Now you can walk into a drugstore to buy toothpaste, a divorce, and shampoo all at the same time. The Dart Drug chain, which has 151 stores and a variety of business interests stretching across the country, has just opened legal centers in three of its Virginia stores.

For $195 you can walk in and buy an uncontested divorce, for $40 a will, for

The concept of legal clinics has been in effect for the last several years in the United States, but this is apparently the first time a ''law center,'' as the Dart lawyers prefer to call it, has brought torts to the drugstores of America.

It may also be the first time in legal history that customers have seen ads in a discount coupon section offering legal actions such as lawsuits and bankruptcy claims. In Dart's Sunday discount coupon section published in local papers, cut-rate counsel on felonies, immigration, and real estate closings is offered alongside the ads for talcum powder, power saws, and mouthwash.

Dart Legal Centers, as they're called, are independently owned by the Vienna, Va., law firm of Zilberberg, Wade & Fuller, three partners who lease the space for their centers from the drug company. Legal ethics forbid non-lawyers from owning, controlling, or profiting from a law firm, for conflict-of-interest reasons among others, so Dart is technically just the landlord.

Mark Zilberberg, a spokesman for the law centers, envisions drugstore law (particularly in shopping centers) as part of the wave of the future. Or the present. He sees it, in effect, as fast-food law: ''I think the public should be afforded this . . . we're a fast-food society today, and time is very important to people. You should be able to get your toothpaste, get your Kleenex, see your dentist, see your attorney, park in the same space, do it in one concentrated amount of time, and have the rest of the time to yourself, and not have to pay for other people's time to meet you in a place that's hard for you to get to. . . . Coming in and buying your Kleenex and your law, that's the way it should be, '' Mr. Zilberberg says.

He hopes that if the concept catches on, beginning with these three stores in the Dart chain, he can move into other Dart stores in the Maryland and Virginia area, perhaps to as many as 12 to 15 within the next year. Each store has 20,000 customers a week or more, he points out, so that gives his centers a potential 60,000 customers who may have some legal needs. In addition, the centers serve 4 ,000 Dart employees at a 20 percent discount (paid by the employees, not the company) so there is additional potential clientele.

Speaking of legal clinics, he says, ''They're not only profitable, they're a very well-received concept. In certain areas (like the West, where ''law stores'' have sprung up), people wonder about clients who don't go to legal centers. They think it's strange. That's why law is changing. That's why we're . . . bringing law to the people. That's how law will be done in the future. A great deal of law deals with the general masses, the general public. It's profitable for everybody. But it's got to be quality and affordable.''

Mr. Zilberberg said those words in an atmosphere of considerable quality - the posh, subdued offices of a prestigious ''downtown'' law firm, LeBoeuf, Lamb, Leiby & MacRae. Zilberberg and his partners have retained LeBoeuf, Lamb, etc., to represent them as counsel in this venture, which the Washington firm has carefully researched for them. ''They represent us with the bar or Dart but in no way guarantee us or do our work,'' he says. He and I are meeting at his request in the moneyed ambiance of LeBoeuf, Lamb's conference room, done in teak and truffle-colored leather, with a huge surfboard-shaped conference table that could seat a football team. Discreet antique prints of New York and London adorn the walls. In one corner a legal secretary is quietly ''Shepherdizing,'' or researching the latest legal rulings, on a Lex legal computer. There are no discount coupons at LeBoeuf, Lamb.

''What we're going out with is quality,'' says Zilberberg, ''bringing that quality to people at affordable prices. It's the affordable law of the future. There will always be a place for firms like LeBoeuf, Lamb, which deal with high-paying corporate clients. But the man on the street, like I was, when I worked with the government - we were virtually priced out of reasonable law.''

Zilberberg, who was special counsel to Rep. Robert L. Leggett of California, has acted as a supervisory management specialist for the Department of Commerce, hearing officer for the Mid-Atlantic Fisheries Management Council, analyst-attorney for the Congressional Research Service, and visiting lecturer at Georgetown University and George Washington University, in addition to maintaining his general law practice in Vienna, Va.

Second half of story is in SLAWM1.

He is a University of Miami law school graduate, with an MS from Forida State in biology and a BA from Pennsylvania State. He is a member of the bar in Florida, Virginia, and the District of Columbia. To provide lawyer-like offices at Dart and staff each of them with a paralegal office administrator and at least one lawyer, he and his partners, Gregory Wade and Vincent Fuller, pooled ''a couple hundred grand.''

When they advertised, he adds, they got 400 applicants for the three lawyers' slots, applicants from the Justice Department, the IRS, and private firms. The incentive was a starting salary of $32,500 plus a slice of the profits.

Mark Zilberberg is a tall, affable man with ash-blond hair who wears a diamond pinky ring. The day we talk he is dressed in navy, black and white houndstooth check pants, a navy jacket, blue designer shirt with the designer's monogram on the pocket, and a navy blue tie with tiny white dots. He carries a battered attache case stuffed with legal papers and wears black wing-tip shoes. We had planned to meet for a breakfast interview, but he arrives and says he's fasting for a religious holiday. So he does the interview on an empty stomach and a lot of energy.

To a question about whether cut-rate legal ads in newspaper coupon sections and drugstore divorces lower the level of professional dignity traditionally attached to the law, he responds: ''No. I think we have to get away from the former concept that coming out with competitive prices is lowering the standards of the profession. It's making it more accountable. . . . I don't think there's any need for secrecy in this profession . . . this is what it is, it's more quality control with law and it makes the profession more accountable.''

Richard Collins, director of communications for the American Bar Association, says the ABA ''has favored the establishment of legal clinics as an alternative for delivering legal services economically to the middle class and making access to lawyers easier. We financed one of the first clinics, in Philadelphia, and have been on the side of the legal clinic movement, although some people in the movement have been quoted as saying that we have not.'' Mr. Collins notes that the ABA does not evaluate the clinics because legal discipline and accountability are the functions of the state bars.

He did cite some instances in Florida in which legal clinics ''had laymen owning and operating them. That's a real no-no. There's a feeling generally that the lawyer-client relationship is confidential, like that of journalist and source or physician and patient, and a third party involved in the proceedings could certainly lessen that relationship. It's further complicated if the corporate ownership were involved in a legal claim . . . a conflict of interest.'' The Florida instances, he says, were corrected when the bar and courts ''came down hard on them.''

Asked whether discount coupons and drugstore divorces make the ABA wince for the professional dignity of the law, Collins says, ''The ABA only winces when 385 members that make up the delegation vote to wince. And there has not been any kind of policy question on this presented to them about the matter of dignity. So there is no official position.''

A matter that concerns one member of a prominent law firm in Washington is the possibility that ''brief and superficial'' counsel in a legal clinic might have disastrous effects for a client with a complex legal problem in which a standard form is not appropriate: certain kinds of wills, for instance.

Collins notes: ''A former president of the ABA made two points about wills: if you get a bum one, you'll never know about it if you're dead, and your heirs might find it out too late. So there has to be great care in that area. The second point is that in the abstract, on simple wills, clinics can theoretically do them much more cheaply than a downtown law firm that specialized, say, in labor or antitrust law, but . . . it is a question of the dedication and care of the people running it.''

The immediate past president of the ABA, Reece Smith, of Tampa, Fla., says of legal advertising among the discount coupons: ''It offends my sense of tradition in the practice of the profession.'' In general, though, he says he supports new methods like legal clinics which ''offer the possibility of good legal services at reduced costs to the public . . . the lawyers might be in a drugstore, but I have to assume the process they used would otherwise be the legal processes'' used in law firms in standard locations.

He suggests that perhaps the more things change in the legal profession, the more they remain the same. ''I'm not sure there's as much change going on as perceived by the media. Legal clinics may be a change, but that depends entirely on what they do and how they operate as to whether there's any meaningful change. It's the same as the legal advertising urged by consumer groups. It doesn't tell you much about the law, it only tells you what the lawyer charges. It's like soap ads - they don't tell you how the soap smells, they only tell you what it sells for.''