Blackleg labour

A strikebreaker (sometimes derogatorily called a scab, blackleg, or knobstick) is a person who works despite an ongoing strike. Strikebreakers are usually individuals who are not employed by the company prior to the trade union dispute, but rather hired after or during the strike to keep the organization running. "Strikebreakers" may also refer to workers (union members or not) who cross picket lines to work.

The use of strikebreakers is a worldwide phenomenon; however, many countries have passed laws outlawing their use as they undermine the collective bargaining process. Strikebreakers are used far more frequently in the United States than in any other industrialized country.

The right to strike is not expressly mentioned in any convention of the International Labour Organization (ILO); however, the ILO's Freedom of Association Committee established principles on the right to strike through ongoing rulings. Among human rights treaties, only the International Covenant on Economic, Social and Cultural Rights contains a clause protecting the right to strike. However, like the Social Charter of 1961, the Covenant permits each signatory country to abridge the right to strike.

The ILO Committee on Freedom of Association and other ILO bodies have, however, interpreted all core ILO conventions as protecting the right to strike as an essential element of the freedom of association. For example, the ILO has ruled that "the right to strike is an intrinsic corollary of the right of association protected by Convention No. 87."

The ILO has also concluded striker replacement, while not in contravention of ILO agreements, carries with it significant risks for abuse and places trade union freedoms "in grave jeopardy."

The European Social Charter of 1961 was the first international agreement to expressly protect the right to strike. However, the European Union's Community Charter of the Fundamental Social Rights of Workers permits EU member states to regulate the right to strike.

...
Wikipedia