Republican Governor Rick Snyder signed the bills into law as soon as they reached his desk, completing in a few days a campaign to make Michigan the 24th U.S. state to prohibit unions from requiring employees to join and contribute dues.
"I view this as an opportunity to stand up for Michigan's workers, to be pro-worker," Snyder told a news conference after he signed the bills.
The laws will take effect 90 days after the end of the legislative session, which means they will probably come into force sometime in April. Existing union contracts will not be changed until they expire, according to a provision of the laws.
In a rapid turn of events, Michigan moved from being a bastion of union influence to joining states, mostly in the South, that have weakened local protections for unions.
The Teamsters union national president, James Hoffa, whose father, Jimmy Hoffa, was one of the nation's most famous labor leaders until he disappeared in 1975 in Michigan, denounced Republican leaders in a speech to the protesters.
"Let me tell the governor and all those elected officials who vote for this shameful, divisive bill - there will be repercussions," Hoffa said, adding the Republicans could be defeated in the next election.
Unions have accused Snyder of caving in to wealthy Republican business owners and political donors such as the Koch brothers, owners of an energy and trading conglomerate, and Richard DeVos, the co-founder of Michigan-based Amway.
Snyder, a former computer company executive who had said "right-to-work" legislation was too divisive for Michigan, changed course last week and announced his support for it.
While labor leaders decried the legislation, Republican Representative Lisa Lyons said during the debate in the House that such laws were not an attack on unions.
"This is the day Michigan freed its workers," she said.
Opponents argue that the measures undermine a basic union tenet of bargaining collectively with employers for better wages, benefits and working conditions. They also allow workers to opt out of a union, potentially reducing membership.
By weakening unions, Republicans also could hurt the Democratic Party, which traditionally receives a significant portion of its funding and grass-roots support from unions.
Supporters of right-to-work measures say some unions have become too rigid and workers should be given a choice of whether to join. They also say a more flexible labor market encourages business investment, citing "right-to-work" states where some foreign automakers have put plants rather than in Michigan.
CRIES OF 'SHAME'
The measures were approved to cries of "shame" from protesters inside the Capitol building, which was closed to visitors when it reached capacity of 2,200, Michigan State Police Inspector Gene Adamczyk said.
An estimated 10,000 more people demonstrated outside in cold and snowy conditions, including members of the United Auto Workers union, and teachers, who shut down several schools in the state to attend the rally.
A few protesters were ejected from the Capitol after they chanted slogans from the gallery during the debate. Protesters tore down two tents set up for supporters of "right-to-work" on the grounds of the Capitol. Adamczyk said six people were arrested after scuffling with officers.
A mixture of pepper spray and tear gas was used on one person, Adamczyk said, although Reuters journalists also saw protesters sprayed with a substance at a government building near the Capitol.
The protests recalled big rallies in Wisconsin nearly two years ago when Republicans voted to curb public-sector unions. Wisconsin never tried to pass "right-to-work" bills.
But Indiana earlier this year became the first state in the industrial Midwest to approve "right-to-work" legislation and several other states are watching the Michigan action closely.
LEGAL CHALLENGES LOOM
Republicans in Michigan were also emboldened by the defeat in the November election of a ballot initiative backed by unions that would have enshrined the right to collective bargaining in the state constitution.
Michigan is home of the heavily unionized U.S. auto industry, with some 700 manufacturing plants in the state. The state has the fifth highest percentage of workers who are union members, at 17.5 percent
The Detroit area is headquarters for General Motors Co, Ford Motor Co and Chrysler, which is majority-owned by Fiat SpA.
The UAW was founded in Michigan after a 1932 protest at a Ford plant in Dearborn left five people dead, increasing public sympathy for industrial workers during the Great Depression and leading to national legislation protecting unions.
Major automakers, which secured concessions from the UAW after nearly going bankrupt during the recession of 2008-09, were careful not to take sides publicly in the fight.
All of the so-called Big Three domestic automakers said they were "neutral" on "right-to-work," even though the Michigan Chamber of Commerce strongly supports it.
"At Ford, we are focused on working with all our partners, including the UAW," the company said in a statement on Tuesday.
Democrats and unions have vowed to challenge the new laws in the courts, to try to overturn them in a ballot initiative and possibly oust through recall elections some Republicans who voted for the measures.
Democratic Representative Douglas Geiss said "right-to-work" laws would lead to a resumption of the battles surrounding the creation of unions decades ago.
"There will be fights on the shop floor if many workers announce they will not pay union dues," Geiss said.
