For some, they cause travel chaos, artificially inflate wages and exert undue power on democratic governments; for others, they offer representation to the voiceless, save jobs from globalization's worst imbalances and stand up to state-led tyranny.
Trade unions remain a fearsome political and economic force around the world, able to mobilize large numbers of warm bodies to man picket lines and pressure politicians. CNBC has compiled a list of the most influential unions.
Posted 20 June 2011
The Congress of South African Trade Unions was founded in 1985 and played a major role over the final years of apartheid, mobilizing workers in strikes and mass protests in the struggle for racial equality.
COSATU forged close links with the African National Congress, post-apartheid South Africa's dominant political party, as well as with the country's communists. Together, this "tripartite alliance" hold a monopoly over South African politics. However, despite their close relationship with Pretoria, COSATU's members remain more than willing to disrupt the government's plans.
In 2010, COSATU and its affiliates brought the country to a standstill, backing a public sector strike that paralysed services as nurses, doctors and teachers demanded wage hikes. Later that year, union opposition saw the famously union-busting US retail giant Walmart given a rough ride in its bid for South African counterpart Massmart
Size matters in industrial disputes, and the All-China Federation of Trade Unions is the world's largest by far, counting 190 million members today. Like many other trade unions, the ACFTU was considered a revolutionary organization upon its formation in 1925. The Chiang Kai-Shek government tried to restrict its activities, and members were imprisoned and executed for sedition.
After Mao Zedong's Cultural Revolution in the 1960s, the ACFTU was banned again, re-emerging after Mao's death.
Today, the ACFTU is being backed by Beijing – sort of. The government introduced new labor laws in 2008, which required international companies to create in-house committees for workers to consult with management. The ACFTU has stepped in to register all these groups with the union, effectively making the creation of union chapters mandatory.
When, in 2006, then-Prime Minister of France Dominique de Villepin announced plans to reform the country's labor laws to create flexible working contracts for young people, he must have expected some resistance from the layers of unions and trade associations that had shaped policy in the country for years. However, the violent street protests mobilized by unions and student groups took many by surprise.
The main French unions, rallied around the largest, the Confederation Generale du Travail, stopped de Villepin's plan dead, but also reignited a debate in France and overseas about the power of the organizations.
Union leaders have done well over the years in France to cultivate an image as popular revolutionaries with links back to the glory days of the Storming of the Bastille. However, as many critics note, their public sympathy is not matched by their membership figures, which have declined to below 8 percent of the workforce, compared to around 30 percent in the UK.
Representing workers at Germany's most recognisable brands and acting as the voice of the country's heavy industry and manufacturing sectors puts IG Metall in an incredibly influential position in the German economy.
At times, it has shown itself to be unusually moderate. In 2008 the union lobbied extensively for an 8 percent pay rise from employers in the engineering business, threatening strikes and other industrial action. However, as the financial crisis began to bite, the IG Metall quickly dropped its demands, agreeing to rises of just 4.2 percent.
However, as the German economy picks up and the manufacturing sector drives growth, the union is once again lobbying for improved conditions.
The Greek government is desperately trying to keep the bailout wolf from the door through asset sales and spending cuts, but the population remains unconvinced and dissent, in the forms of popular protests, continues.
Members of ADEDY, the Civil Servants Confederation, perhaps have the most to lose, as public sector job cuts and the privatization of state assets loom. Along with the General Confederation of Labor, the largest private sector union, ADEDY has been calling for general strikes, shutting down services in the country at a time when it needs every basis point of growth that it can get its hands on, as well as delaying operations at key assets, such as ports, that the government will need to sell.
Implementing the government's austerity and recovery packages will require no small degree of hardship in Greece, and the unions' ability to mobilize people around the message of anti-cuts solidarity could be both a significant barrier to reform and a potential risk to the wider European banking sector.
On January 30, members of the state-run Egyptian Trade Union Federation met in Tahrir Square in Cairo, the stage for the later overthrow of Hosni Mubarak's government. Four unions signed a new declaration creating the Federation of Egyptian Trade Unions, ending state control and creating a powerful new force for change in the early stages of the country's uprising.
The FETU immediately called for a general strike in solidarity with the protestors who were calling for the end to the Mubarak regime. In the days following the president's resignation, as the country tried to find a consensus government, the unions continued to lobby for labor reform, workers rights and human rights, and played a formative role in the beginnings of the post-Mubarak era, analysts have said.
Union leaders of the old school are often referred to as 'dinosaurs', and few labor organizations appear less revolutionary and progressive than the Confederation of Mexican Workers (CTM), the largest union in Central America.
The CTM was effectively in government as part of the Partido Revolucionario Institucional (PRI), which held power in Mexico between 1929 and 2000. When, in 2000, the PRI lost in open elections for the first time since the Mexican Civil War, the CTM was suddenly removed from top-level politics in the country, and has not regained its power since.
Critics say that today its weakened role and conservatism have caused it not only to stop genuinely supporting workers' rights, but also to block the formation of fresher unions, holding the development of labor rights in the country in check.
Although the fall of the Berlin Wall in 1989 for most marks the symbolic end of the Soviet domination of Eastern Europe, the actions of a trade union founded in the Gdansk shipyards in Poland and led by a poorly-educated electrician set in motion a process that fatally undermined the Kremlin's influence.
Solidarity, led by the charismatic Lech Walesa, who would later become Poland's president, had amassed more than 9 million members within a year of its formation, evolving from a trade union into a social protest movement that resisted martial law and forced the Soviet-backed government to agree to elections.
Today, Solidarity claims around 720,000 members and operates as a more traditional labor union.
The National Union of Rail, Maritime and Transport Workers (RMT) is far from the largest union in the UK, and arguably it is far from the political mainstream. The main British opposition, the Labor Party, maintained close links to the unions even during its more centrist years in power between 1997 and 2010. However, for headline-grabbing antics and financial sector disruption, the RMT punches well above its weight.
RMT head Bob Crow has become something of a cartoon villain for London during his nine years in the role, instigating a string of strikes by workers on London's Underground, which cost the city around 50 million pounds per day of industrial action.
While this is pocket change compared to the amount raked in by the city's banks daily, Crow is known as a wily operator who is unafraid of threatening strikes during major events and holidays. With the Olympic Games coming to London in 2012, Londoners expect yet more brinkmanship from the RMT.
Despite lacking the revolutionary credentials of some international bodies, unions in the USA have their own dramatic history, and few have as colorful a mythology as the International Brotherhood of Teamsters, which has been organizing elements of labor force in the States for more than a century.
Despite all of their achievements in creating better labor contracts and improving workers' rights, the Teamsters are probably more famous for their links to the superstars of organized crime – Al Capone and Roger Touhy – and for the disappearance under suspicious circumstances of organizer Jimmy Hoffa in 1975.
Hoffa is presumed dead, but his body was never found, and rumors and conspiracy theories abound as to his fate.