Time was, a shopkeeper caught doing business on Sunday could wind up paying a fine or even spending the night in jail.

These days, to hear business owners and lobbyists tell it, failing to serve shoppers, diners and drinkers seven days a week is akin to economic malpractice.

Just ask Joe Rillo, acting president of Rillo's Restaurant in Carlisle, Pa., a family-owned Italian eatery that once shut its doors on Sundays, figuring people wanted to stay at home.

Now, Sunday is the restaurant's third-biggest day of the week.

"It's definitely a mainstay for us," Rillo said. "People come in from a little further away. They have time to travel. A lot of times it's families coming for special occasions. We have regulars who come every Sunday."

The panicked reaction among Virginia businesses to the state's accidental resurrection of an old "blue law" allowing employees to demand Saturday or Sunday as a "day of rest" highlights the extent to which the U.S. economy now relies on a seven-day week.

It also illustrates the cultural distance the nation has traveled from its Puritan roots, when Sunday meant observing the Christian Sabbath and staying far away from the workplace.

Blue laws, which date to colonial New England, have been under assault for at least a generation, mainly from business groups eager to take advantage of what has become a major shopping day for increasingly over-worked and over-scheduled American families.

"The moment when we secularized Sunday . . . happened a long time ago and it's highly unlikely at this late stage that we can consider any sort of return," said Witold Rybczynski, author of "Waiting for the Weekend."

According to data from research firm ACNielsen, Sunday has become one of the biggest shopping days of the week, with close to 17 percent of all grocery store trips and over 18 percent of all trips to big chain stores such as Wal-Mart and Target taking place that day.

About 11 percent of retail sales take place on Sunday, according to the International Council of Shopping Centers -- about the same as Monday, Tuesday and Wednesday but significantly less than the nearly 24 percent that take place on Saturday.

In a 2001 report, the Bureau of Labor Statistics estimated 10.4 million employees "usually work on Saturday" and 2.7 million "usually work on Sunday." And about 5.9 million employees usually work both days, compared with 82 million who work weekdays only.

Frank Badillo, a senior economist with Retail Forward Inc., a market research firm, said small businesses will suffer most if the Virginia law goes into effect. A judge on Friday issued an injunction blocking the law for at least 90 days.

"The mass retailers such as Wal-Mart have gone to 24-hour service and put pressure on anyone else in the convenience business to match them" by staying open around the clock and seven days a week, Badillo said. "It's going to make it more difficult for mom-and-pop retailers to compete against the big players that can staff a store 24 hours despite the demands employees might make." Employers with only a few workers could be forced to close on Sundays by a worker or two demanding Sunday off.

Mike Niemira, chief economist at the International Council of Shopping Centers, said Sunday shopping developed over the years out of convenience. Previously, consumers did most of their shopping earlier in the week, he said. This is still the case in localities with enforced blue laws -- such as Bergen County, N.J.

For the most part, blue laws banning Sunday shopping, where they still exist, are largely ignored. That is not the case, however, with blue laws banning Sunday liquor sales. But even those laws are under direct assault.

The liquor industry has been mounting a vigorous campaign to wipe out prohibitions against Sunday sales that remain on the books in many states. And the industry has been remarkably successful, according to Peter Cressy, president of the Distilled Spirits Council.

In the past 2 1/2 years, Cressy said, his organization has helped change Sunday liquor laws in 10 states. Tomorrow, people in Virginia and Rhode Island will be able to buy liquor in stores for the first time ever on a Sunday.

Cressy said his group has made three basic arguments in its campaign: that busy shoppers should be able to buy liquor whenever it is most convenient; that higher taxes on liquor mean more revenue for states with Sunday sales, and that legislating Sunday as sacrosanct can be offensive to non-Christians.

"In the 21st century, it just doesn't seem appropriate that the state should decide what day people should celebrate the Sabbath," Cressy said. He added that the repeal of blue laws generated an additional 4.4 percent in liquor sales nationwide over the last year.

Richard Bank, head of the AFL-CIO's office of collective bargaining, said unions are locked in constant battles with corporate management over forced overtime, which can include demanding that employees work weekend shifts.

"During the economic downturn, employers were very reluctant to hire . . . so when there were economic spurts, and demand for products and services went up, instead of hiring people they put pressure on employees to work extra overtime."

Mandatory overtime was a key issue when Verizon workers went on an 18-day strike in 2000; the workers won significant reductions in forced overtime. Nurses in the Service Employees International Union have been battling with hospitals in several states over mandatory overtime.

While many Americans have grown accustomed to stores being open on Sunday, the trend toward seven-day-a-week commerce has not been without controversy. The decision last year by Family Christian Stores, a bookstore chain based in Grand Rapids, Mich., to open for several hours on Sunday afternoons, for instance, stirred up bad feelings.

In Ohio, shopper Diane Dhawan told the Cleveland Plain Dealer last year that she was upset by the decision. "I was kind of shocked," she said. "If Christians are supposed to show the way, I think it's kind of backing off what we're supposed to do. . . . Now, they're giving in. That's discouraging."

A Family Christian Stores official did not return a call for comment. The company's president told the Plain Dealer last year that the store decided to open Sundays in order to help as many people as possible.

A customer leaves a drugstore on King Street in Alexandria in 1961. A sign lists goods prohibited from sale on Sunday because of Virginia's "blue laws."A pedestrian walks past Paul Revere Beverage in Somerville, Mass., on Sunday, Jan. 4. Liquor store owners in some Massachusetts communities now have the option of staying open Sundays to sell alcoholic beverages.