The United States Supreme Court has ruled that gay and transgender workers are protected from discrimination by their employers.

In a 6-3 majority decision likely to have far reaching effects, the court, which has a conservative majority, held that the federal Civil Rights Act 1964, which prohibits discrimination based on sex, had to be read as including sexual orientation and gender identity.

Three cases were appealed to the court. They involved Gerald Bostock from Georgia, fired from his job as a child welfare services co-ordinator after his employer learned he had joined a gay recreational softball league; the late Donald Zarda, a skydiving instructor from New York, dismissed after joking with a female client that she should not worry about close physical contact because he was 100% gay, who won before the state courts; and Aimee Stephens, who had previously presented as a man at her work for a firm of funeral directors and was sacked after she began coming to work as "my true self" in women's clothes.

In each case the employers, supported by the Trump administration, argued that the 1964 Act had never been intended to apply to such cases. However Justice Neil Gorsuch, a Trump appointee, writing for the majority, ruled that it was impossible to act against such employees without discriminating on the basis of sex. On a textual interpretation of the Act, it covered such cases even if the original drafters had not envisaged that.

The ruling is being seen as a major win for LGBT workers and campaigners.