Unions will be given the right to expel members for belonging to a political party under proposed new laws.
The union law change follows a European ruling
It comes after train drivers union Aslef defeated the UK government in the European Court of Human Rights over the expulsion of a member of the BNP.
The UK government argued the union could not exclude someone for belonging to a legitimate political organisation.
But the European court said Aslef had the right to expel members whose views were incompatible with its stated aims.
The case centred around Virgin train driver Jay Lee, who was expelled by Aslef after standing unsuccessfully as a BNP candidate in 2002.
Mr Lee won the right to remain a member of Aslef at two employment tribunals, which both said that a union could expel someone because of their conduct, but not because they were a member of a particular political party.
But the European Court over-ruled the tribunals, saying Mr Lee would not suffer financially as a result of being expelled, as Aslef did not operate a closed shop and he was free to join another union.
In background documents issued with the Queen's Speech, the government said its new Employment Bill would amend trade union membership laws "in the light of the European court judgement in Aslef v UK".
Under proposed new legislation, unions will be able to "expel members on the basis of their membership of a political party," it added.