Johannesburg - Zwelinzima Vavi will hear on Friday whether his suspension from Cosatu will be set aside.
The Johannesburg High Court is expected to hand down judgment in the matter at 10am.
In August last year, Cosatu said Vavi had been put on special leave pending the outcome of a disciplinary hearing relating to his affair with a junior employee.
In July, the employee accused him of rape. He said they had an affair. The woman subsequently withdrew a sexual harassment complaint against him.
Following Vavi's suspension, the National Union of Metalworkers of South Africa (Numsa), an ally of his, lodged an application in the Johannesburg High Court, challenging the decision.
Vavi then lodged papers to be added as an applicant in Numsa's challenge. In these, he asks the court to grant him an interim order interdicting and restraining Cosatu from enforcing any decision taken at its CEC meeting in August.
He wants final relief to review and set aside the decision to suspend him and institute disciplinary proceedings.
Legal teams for Vavi and Numsa argued last week that the way the decision was taken to suspend the general secretary was undemocratic and a breach of Cosatu's constitution.
Cosatu argued that it used a longstanding practice of taking majority rule without putting it to a vote.
Vavi on Thursday said he would not be at the judgment because his daughter had been in a car accident in Queenstown in the Eastern Cape.
He is still facing internal disciplinary procedures and his hearing is expected next month. - Sapa