Mr Shahzad claims that up to 100 Asian constituency party members were illegally excluded from a number of selection meetings that eventually led to Mr Kaufman's reselection and endorsement by the national executive committee.
Labour suspended Mr Shahzad pending an inquiry after a BBC documentary examined the issue earlier this year. Others who had taken part in the film were also suspended.
The writ against Mr Sawyer will seek an injunction - expected to be heard on Thursday - aimed at preventing Labour from finally expelling Mr Shahzad. The writ claims Mr Shahzad's expulsion would be illegal and that Labour is in breach of its contract to him as a party member.
If the injunction is granted, Mr Shahzad, a nominated representative of Brent East constituency, will be free to speak at the party conference next week on a motion condemning the party for suspending up to 5,000 members.
Ken Livingstone, the Labour MP for Brent East, currently chairs the Campaign Against Labour Party Expulsions, formed to combat what it believes is a "racist witchhunt".
Mr Shahzad's solicitor, Louise Christian, said: "We will be arguing that a Labour Party member cannot be disqualified on matters of opinion."
The party is also accused of breaching European human rights laws on free speech. Mr Shahzad, a founder of the anti-expulsions campaign, said: "We have to show the party we are serious and that the black and Asian community have equal membership rights."
A Labour spokesperson denied all allegations of discrimination.Reuse content