Habergham High School and Ormskirk Grammar School, both comprehensive schools in Lancashire, have had the system for 13 years. Applications are shuffled and numbered by one council, while another reads out numbers from a set of random selection tables.
Three families - one from Ormskirk and two from Burnley, where Habergham is situated - have mounted a legal challenge to the policy, which was first revealed in the Independent earlier this month. Applications for judicial review will be lodged in London today for the Ormskirk case and later this week for the Burnley case.
Only children with brothers or sisters at the schools have an automatic right of entry, although a few pupils are admitted on medical grounds.
Both the schools are former grammar schools - Ormskirk chose not to change its name when it went comprehensive - and both are oversubscribed. They are both close to other local comprehensives, making it difficult for them to select on the basis that children should attend their nearest school.
Lancashire County Council was warned last summer by John Patten, Secretary of State for Education, that its policy was unworkable and it has been consulting parents on alternatives. However, some parents who do not live near the school of their choice want to keep the system.
The parents of children who have failed to get into their nearest schools do not agree. Andrew Visser, whose son Christopher has been denied a place at Habergham despite living five minutes' walk away from the school, is one of those who has decided to go to court.
'There are other schools on the other side of town that parents can send their children to. They are pandering to these parents because they are unwilling to use their local schools. Why should we lose out as a result?' he asked.
Stan Wright, who chairs the county's education committee, said that parents and schools had wanted a lottery system when they first went comprehensive.
'This isn't the authority saying this is what it will do. This is the community saying this is what it wants. Now we are responding to the Government saying the community can't have that,' he said.