A new gun ordinance in Chicago that officials say is the strictest of its kind in the country went into effect on Monday.

The ordinance was pushed through quickly by Mayor Richard Daley and the City Council after the U.S. Supreme Court last month made the city's 28-year-old handgun ban unenforceable. The high court ruled that Americans have the right to have guns in their homes for protection.

The ordinance permits residents to have only one working gun at a time in their homes and prohibits them from stepping outside, even onto their porches or in their garages, with a handgun.

Following the lead of Washington, D.C., which enacted a strict ordinance after the Supreme Court struck down its gun ban two years ago, Chicago also requires prospective gun owners to take a class and receive firearms training.

Chicago's ordinance also bans gun shops from setting up shop in the city and bars anyone convicted of a violent crime, domestic violence or two or more convictions for driving under the influence of alcohol or drugs from owning a handgun.

Also starting Monday is a 90-day grace period in which residents who owned handguns illegally during the ban can register them without penalty.

Chicago's ordinance was widely criticized by gun rights advocates, who have said the city is simply trying to make it as difficult as it can for people to own guns and putting up unconstitutional roadblocks in their way. They promised lawsuits and last week, even before the ordinance went into effect, at least two lawsuits were filed challenging the constitutionality of the ordinance.

Businesses have added 4.5 million workers under a new program that provides tax breaks for hiring unemployed workers, the Treasury Department said Monday.

It is unclear, however, how many of those workers would have been added without the tax break.

President Barack Obama signed a law in March that exempts businesses hiring people who have been unemployed for at least 60 days from paying the 6.2 percent Social Security payroll tax through December. Employers get an additional $1,000 credit if new workers stay on the job a full year.

Treasury released a report Monday estimating that from February to May, businesses added 4.5 million workers who qualify for the tax breaks. Those businesses are projected to save $8.5 billion in taxes.

Immigration to rich countries dropped during the global economic crisis, reversing five years of annual increases as the demand for labor fell, the Organization for Economic Cooperation and Development said Monday.

A report showed that 4.4 million people migrated to the OECD's 31 member countries — the world's most developed economies — in 2008. That is a drop of about 6 percent from the year before.

The fall reverses five years of annual increases of 11 percent, the OECD said in its International Migration Outlook 2010.

National data suggest that international migration fell again in 2009.

Unemployment among male immigrants has risen more than among native counterparts because many immigrants worked in industries badly hit by the crisis, such as construction, hotels and restaurants, the OECD said. Still, few are returning home, it said.

In some countries, employment of female immigrants has risen as women take jobs to make up for lost income of their unemployed spouses, it said.

Law firm merger activity picked up after a sluggish first quarter in part due to a renewed increase in transatlantic marriages between large domestic firms and those headquartered in England.

Among the 10 mergers reported last quarter by legal consultancy Hildebrandt Baker Robbins -- one more than during that time frame last year -- was the union of Washington stalwart Hogan & Hartson and London-based Lovells to form Hogan Lovells, which the report characterized as the second-largest since Hildebrandt began tracking quarterly merger activity.

A second cross-border marriage of equals, between Chicago-based Sonnenschein Nath & Rosenthal and London's Denton Wilde Sapte, was announced last quarter but is not included in that figure because the merger will not be completed until later in the year.

Industry analysts say that after a period of caution, U.S. firms are once again looking for markets in which to expand -- and the obvious one for some is London, where many firms specialize in the kind of corporate transaction work that has long been the bread and butter of New York.