Former Constitutional Court judge Johann Kriegler's organisation, Freedom Under Law, is expected to file papers in the High Court in Pretoria on Wednesday to challenge a decision by the Judicial Service Commission (JSC).
SABC radio news quoted Freedom Under Law spokesperson Niall Gahan as saying the long-awaited papers had been finalised.
The organisation, chaired by Kriegler, wants the court to set aside its decision not to take action against Cape Judge President John Hlophe.
Kriegler has said the JSC did not pursue the matter fully before making its decision.
"That is the basic malfunction - it has left poor Judge Hlophe with a cloud over his head," Kriegler reportedly said.
The judges of the Constitutional Court last year laid a complaint with the JSC against Hlophe for allegedly making an inappropriate approach to two judges regarding a ruling on Jacob Zuma before he became president.
But after lengthy debates, a reconstituted JSC this year decided not to go further with the matter and Hlophe ended his special leave by returning to work.
This had caused "great harm" to the administration of justice, said Kriegler.