Furious, the customers would have gotten raging drunk--if they could have.

It was March 29, 1896--the day Brooklyn unintentionally became a "dry" city, thanks to a new law meant to curtail drinking on Sundays. Sure, saloon owners knew they would lose a substantial part of their income. But there was another unintended consequence. Because many saloons never closed, newly established proprietors threw their door keys into the East River for good luck, not thinking they would ever need to lock up. TheNew York Times reported that on March 28, saloon keepers across Brooklyn were hiring locksmiths to replace long-lost keys.

Regardless of the century, every year brings laws that affect companies across the country, from income tax laws to internet regulation. And legislation that gets passed in one state often influences what will get passed in another. To keep you up-to-date on laws that could change how you do business, here's a look at some of the new rules and regulations being implemented this year.

Hiring illegal immigrants may actually become illegal. Arizona Gov. Janet Napolitano signed the Fair and Legal Employment Act, which suspends and revokes the business licenses of Arizona employers who "knowingly" or "intentionally" hire illegal immigrants. The sticking point is what constitutes "knowingly," which the law doesn't really define.

But Arizona is hardly alone in confounding employers. As 2007 neared a close, according to the National Conference of State Legislatures, at least 1,562 pieces of legislation related to immigrants and immigration had been introduced among the 50 states. Of those bills, 244 of them became law in 46 states. Some cities, including San Francisco; Austin, Texas; Houston and Seattle, are being more lenient toward illegal immigrants. Others aren't. So if you think you might have employees on your payroll illegally, find out how the law is changing in your state of operation.

Eliminate the mercury, Minnesota. If you live in Minnesota, you're probably aware your state has been on a quest for years to rid the state of mercury. In 2007, as in past years, several products were mandated to be mercury-free, including stoves, barometers, cooking thermometers, over-the-counter pharmaceutical products, cosmetics, toiletries and fragrances. So far, Mercury car dealers are still safe.

Keep your employees toxin-free. A new federal EPA law limits the emissions of toxic chemicals at all auto-body refinishing shops. All of your employees will need to complete training in the proper use of refinish materials and be certified through a national certification body. And there are more esoteric rules like using an HVLP--high-volume, low-pressure--spray gun, which means more paint stays on the car and less goes everywhere else, like on your employees.

New law might have Motel 6 rethink its slogan, "We'll leave the light on for you." In December, President Bush signed the Energy Independence and Security Act of 2007. The lighting industry is required to create a light bulb that uses 25 to 30 percent less energy by 2014. It should be a boon for the compact fluorescent light bulb industry, and not so great for incandescent light bulb manufacturers, since their product wastes 90 percent of its energy as heat instead of light. The energy act is also a windfall for companies making ethanol and other biofuels.

Check the label on that flag. Selling flags in Minnesota? You can't, unless they're manufactured in the U.S.

Minimum wage gets a boost. This year, employers in New Mexico are now paying their employees $6.50 an hour and gearing up to pay $7.50 an hour starting next January 1. California's minimum wage just went up to $8 from $7.50, tying Massachusetts for the highest state minimum wage in the nation. Meanwhile, every January 1, the minimum wage will be adjusted for inflation in Arizona, Colorado, Florida, Missouri, Nevada, Ohio, Oregon and Vermont.

Scrap dealers in Tennessee may soon thwart the bad guys. Legislation still hasn't been finalized, but is expected to pass soon. If it does, scrap metal dealers will have to register with the state and record personal and vehicle information for each person making a scrap metal sale. Dealers will also be forbidden from paying cash to unauthorized sellers of copper and various other items. Thieves, particularly in Chattanooga, have been crawling under houses to steal pipes and have removed wiring and plumbing from unfinished construction projects. They're even lurking at the top of buildings, taking wire from industrial-sized air conditioning units.

No smoking on the job. If you're in Illinois and have employees, they can't smoke at work. Period. Illinois became the 22nd state in the nation to implement the no smoking rule.

Sick days get paid. In 2006, a law passed in San Francisco requiring businesses to give employees paid sick days. Throughout 2007, states and some cities got into the act, introducing legislation that will likely be enacted in 2008. Maine, Massachusetts, Vermont, Minnesota, Pennsylvania, Maryland, Washington, DC, North Carolina, Florida, Missouri, Minnesota and Connecticut all are working on getting laws passed for 2008. Ohio, West Virginia, Rhode Island, Montana and Alaska are considering similar legislation in 2008 that would go into effect in 2009.

Congratulations? You're an adult entertainment facility. Previously, if pornographic materials were your "primary business," you were classified as an adult entertainment facility. Now, however, the term applies if as little as 25 percent of your sales come from sexually explicit materials.

Say cheese. In Greeley, Colorado, pawnbrokers are now required to take photos of all customers who sell goods. The reasoning is that the photos can help track down the criminal elements if the sales item turns out to be stolen.

Michigan encourages entrepreneurship. They aren't only featuring actor Jeff Daniels in commercials touting the state's strengths. To jumpstart the flagging economy, a new law will give qualified startups tax incentives, such as a tax exemption on real and personal property.

Think twice before offering gift cards to your customers. If your business is in California, customers with less than a $10 balance on their gift card have the legal right to receive the balance in cash. In Illinois, any of your customers who buy a gift card can't have the value reduced on it, as long as they use it within five years.

Background checks? Whoa, Nellie, if you're in Washington state. You can run a credit report on an employee if the information is "substantially job related." So if you're hiring a security guard or someone with access to employee financial or personal information, you're fine. But if you're hiring a waiter, a driver or a warehouse factory worker and you obtain a credit report, you're probably breaking the law.

New York entrepreneurs get to combat identity theft. That's the optimistic way to look at it. Pessimistically, you may have a lot of extra paperwork. The new law disallows using Social Security numbers for authentication purposes only. For instance, you can no longer require employees to use their Social Security number as a password to access your company website.

Guns don't kill people, but lunatic employees might--using guns. It hasn't happened yet, but last year in Georgia, the NRA began reviving a campaign to prohibit businesses from telling employees they can't keep firearms in their cars. At issue is whether employees have the right to keep whatever they want in their own property--their cars--or whether entrepreneurs have the right to decide what happens on the property of their business. Either way, the issue is expected to be settled this year.