Page "Private investigator" Paragraph 14

During the union unrest in the US in the late 19th century, companies sometimes hired operatives and armed guards from the Pinkertons and similar agencies to keep strikers and suspected unionists out of their factories.

The most famous example of this was the Homestead Strike of 1892, when industrialist Henry Clay Frick hired a large contingent of Pinkerton men to regain possession of Andrew Carnegie's steel mill during a lock-out at Homestead, Pennsylvania.

Gunfire erupted between the strikers and the Pinkertons, resulting in multiple casualties and deaths on both sides.

Several days later a radical anarchist, Alexander Berkman, attempted to assassinate Frick.

In the aftermath of the Homestead Riot, several states passed so-called " anti-Pinkerton " laws restricting the importation of private security guards during union strikes.

The federal Anti-Pinkerton Act of 1893 continues to prohibit an " individual employed by the Pinkerton Detective Agency, or similar organization " from being employed by " the Government of the United States or the government of the District of Columbia.