As someone born in the North East of England, I am no stranger to either coal mining or the need for Unions to protect the rights of workers. This story therefore has a lot of resonance with me, even if the coal mining in question took place over 130 years ago and several thousand miles away in Pennsylvania state.
The story goes that in the 1870s a group of Irish coal miners, all part of an Irish Pro-Union organisation called the Molly Maguires, were accused of murder. It is such a well known tale that there was even a movie about it starring Sean Connery. Accounts agree that the circumstances of their arrest and trial between 1876 and 1878 were somewhat shady with an investigation carried out by the Pinkerton Detective agency (a private concern) and arrests made by the Coal and Iron Police (a paid militia run by the companies that owned the mines). There were also suspicions of Jury tampering (the composition of the jury was composed of ethnic groups such as German and Welsh immigrants who had a distaste for the Irish) and the judge was reputed to have a heavy anti-Molly bias.