How does the United States count the cost of at least 11 million immigrants living and often working outside the law?

For business groups - now urging a path to citizenship or other legal status for such workers - it's the lower cost of a head of lettuce, new home construction, or a restaurant tab, because these people will do the work that Americans won't.

For local officials across the country - no longer just those near a border - it's the strain illegals pose to schools, hospital emergency rooms, law enforcement, and other social services, driving municipal budgets deep into the red.

For illegal immigrants and their supporters - rallying by the hundreds of thousands around the country in the run-up to this debate - the issue is freedom from fear.

But one of the most pervasive costs of a broken immigration system, acknowledged by all sides, is the cost of deception.

"Today's immigration policy is almost founded on lies," says Mark Krikorian, executive director of the Center for Immigration Studies. "It presupposes lying by almost everyone involved."

Bringing honesty to the system without deporting millions and jeopardizing major sectors of the US economy is the tough task before the Senate Judiciary Committee, as its 18 members struggle toward consensus on a new strategy for immigration reform.

Senate majority leader Bill Frist has set Tuesday to begin debate on the topic. That means the Judiciary panel has one last day - Monday - to work out a comprehensive plan, including a new guest worker program and a path to citizenship for those already working illegally. If it fails, Senator Frist will introduce his own plan Tuesday, which, like the House bill, aims only to gain control of US borders.

Pro-immigration demonstrators, meanwhile, are expected to rally at the Capitol Tuesday, following a 500,000-strong rally for illegal-immigrant rights in Los Angeles, and other protests in Denver, Phoenix, Milwaukee, Chicago, Philadelphia, and Tucson, Ariz. Organizers say they'll march in 30 more cities before the Senate vote next month.

Last year, the immigration debate on Capitol Hill was overshadowed by the Minutemen - an armed civilian posse out to stop illegal border crossings. But the prospect of congressional crackdown on illegal immigrants, including the enforcement of penalties against employers who hire them, is drawing record numbers of immigrants into the streets, with a powerful coalition of business, church, and union groups behind them. Their message: These are good people who work hard, pay taxes, and should not be treated as felons.

"Polls show that people do recognize the value of immigration, including illegal," says Peter Schuck, a professor at Yale Law School in New Haven, Conn. "On the other hand, it is a violation of law, and people have just found strategies to live with it."

For employers who hire illegals, that means not looking too closely at documents. Only three employers were fined for hiring illegals in 2004, down from 417 in 1999, according to a report by the Government Accountability Office in August 2005.

"It's a dysfunctional system that breeds disrespect for the law," says John Gay, senior vice president of government affairs and public policy at the National Restaurant Association and a co-chair for the Essential Worker Immigration Coalition.

"Many employers see this as a game: If they ask people to provide proper documents, they leave." Restaurants that knowingly violate the law, he adds, gain an unfair advantage.

Not only is there a disincentive because there is no enforcement of the law, but if employers examine someone's documents too closely, they can be pursued by the Justice Department for employment related discrimination.

"We are digging ourselves into a hole by turning a blind eye to illegality," says Jared Bernstein, director of the Living Standards Program at the Economic Policy Institute. "All kinds of unintentional consequences surface when you do that, including paving the wayfor armed vigilantees on the border."

One of the most toxic issues in the debate is whether the flood of immigrants, especially the 500,000 undocumented workers who enter the country each year, are driving down prospects for low-skilled Americans. A new report by the Center for Immigration Studies finds that states with the largest increase in immigrants also saw larger declines in natives working.

"This isn't just some parlor game for economists: Low-skill native workers are hurt by flooding the market with immigrants," says Mr. Krikorian.

Another point of deception in the system is the limited enforcement the nation's immigration laws. "We don't allow state police making traffic stops to ask about a driver's legal status," says Sen. Jeff Sessions (R) of Alabama, a member of the Senate Judiciary Committee. "What does that tell you about how serious we are about enforcing our immigration laws?"

Last week, business owners in Costa Mesa, Calif., called on the City Council to suspend a new policy that allows police to enforce federal immigration laws, which they say are hurting business. Nearly every state has proposals pending to address illegal immigration.

"This is a justice issue: You can't have 11 million people being vulnerable and exploited," said Joshua Hoyt, executive director of the Illinois Coalition for Immigrant and Refugee Rights, in a conference call after Chicago demonstrations last week.

"There is a politicization of this issue in the immigrant community in a way that has not happened in the past," he added.