The British Humanist Association (BHA), which has launched the action with a local campaign group, is applying for judicial review of the decision by a London council, Richmond, to hand £10m of land and assets to the Catholic church to set up two new voluntary-aided religious schools, one primary and one secondary.

The case will hinge on a relatively narrow piece of legislation, an amendment to the Education Act passed last year, which compels councils looking to set up a new school to also seek proposals for a free school, with the competing bids decided on by the Department for Education. But the BHA says it highlights a wider issue of councils too often waving through state-funded faith schools, with the last five years seeing two-thirds of them set up without any alternatives being offered.

Andrew Copson, chief executive of the BHA, which opposes all faith schools, said: "Although it's a local case, it really is representative of a national pattern, which sees state-funded religious schools opening by the back door, without competition, without the possibility even for local people to make their voices heard.

"All legal cases are, to an extent, forced on technicalities but the principle in this is clear: any new schools should be subject to democratic control and public will. Handing over public money to religious organisations essentially behind closed doors is not a good way for authorities to behave," he said.

The BHA is allied in the high court case, scheduled to run today and tomorrow, with a local group, Richmond Inclusive Schools Campaign. Massed against them are Richmond council – which notes that a web survey of more than 4,000 locals, albeit self-selected, found 67% approval for a Catholic secondary school – as well as the diocese of Westminster and Michael Gove, the education secretary, who has backed Richmond.