Laverty, who has won the Palme d’Or for his collaborations with director Ken Loach, was detained by officers in Edinburgh on Monday.
It is understood that Laverty faces a terrorism charge for wearing a T-shirt stating: “Genocide in Palestine time to take action”.
In other cases, the garment has been alleged to be in support of Palestine Action, a protest group proscribed as a terrorist organisation by the Labour Government in July.
Starting with the first Red Scare, the US government spent decades trying (with some success) to force unions to not be even slightly socialist, to the point of letting Mafia-controlled unions like the Teamsters gain members. The corrupt and useless AFL/CIO was set up as a trades-based (and racially segregated) alternative to the IWW.
The Thatcher government waged war on the unions in the UK, but with less success; some are still fairly leftwing. Meanwhile, Labour centrists have had a long policy of trying to reduce the influence of unions on the party, as well as purging its membership of socialists.