After the Sheffield Outrages in 1867 the head of the Conservative government, Earl of Derby, decided to set up a Royal Commission on Trade Unions. No trade unionists were appointed but Robert Applegarth was chosen as a union observer of the proceedings. Applegarth worked hard checking the various accusations of the employers and providing information to the two pro-union members of the Royal Commission, Frederic Harrison and Thomas Hughes. Applegarth also appeared as a witness and it was generally accepted that he was the most impressive of all the trade unionists who gave evidence before the commission.

Frederic Harrison, Thomas Hughes and the Earl of Lichfield refused to sign the Majority Report that was hostile to trade unions and instead produced a Minority Report where he argued that trade unions should be given privileged legal status. Harrison suggested several changes to the law: (1) Persons combining should not be liable for indictment for conspiracy unless their actions would be criminal if committed by a single person; (2) The common law doctrine of restraint of trade in its application to trade associations should be repealed; (3) That all legislation dealing with specifically with the activities of employers or workmen should be repealed; (4) That all trade unions should receive full and positive protection for their funds and other property.

Applegarth led the campaign to have the Minority Report accepted by the new Liberal government headed by William Gladstone. He was successful and the 1871 Trade Union Act was based largely on the Minority Report.