The sex-for-grades corruption trial against law professor Tey Tsun Hang resumes Monday, after an adjournment of about two months.

The associate professor from the National University of Singapore (NUS), who is conducting his own defence, is set to take the stand.

He is expected to give his account of the circumstances under which his statements to the Corrupt Practices Investigation Bureau (CPIB) were made, among other things.

The 41-year old claims that CPIB officers had used heavy-handed tactics to force "confessions" out of him while he was under medication. A trial within a trial was underway before the adjournment, to determine if statements containing those confessions can be admitted as evidence.

Tey, who is married, has been allowed to call 16 witnesses, five of whom are expected to testify in the trial within a trial.

They include Alexandra Hospital doctors, and NUS law dean Simon Chesterman. NUS provost Tan Eng Chye is also on the witness list, along with other administrative and teaching staff from the university.

Former students, including Supreme Court Assistant Registrar Colin Seow - who allegedly gave a printer to Tey - could also take the stand.

Tey faces six charges of corruptly obtaining gifts and sex from his former student, Ms Darinne Ko Wen Hui, 23, in exchange for improving her grades.

He has tried to show that Ms Ko - who is now working in an American law firm - deserved her grades and he never asked for the gifts, which he says were tokens of her affection.

The crux of the prosecution's case, however, is that whatever their relationship, Tey's intentions were corrupt and he had taken advantage of his young student.

Tey was suspended by NUS in July last year after he was charged in court, but is said to be still receiving full pay, which is believed to be $15,000 a month.

The hearing before Chief District Judge Tan Siong Thye is set to go on for the next three weeks.