Defence Minister Mohamad Sabu's son, Ahmad Saiful Islam, has been ordered to enter his defence over a drug charge.

The substance Ahmad Saiful is accused of consuming is THC, or tetrahydrocannabinol; it is the best-known psychoactive component in marijuana.

He was accused of committing the offence involving the substance at an entertainment centre at Hotel W in the nation's capital, at around 2.05am on Jan 5, last year.

The Kuala Lumpur Magistrate's Court today made the ruling as the accused stood calmly in the dock in the packed courtroom this morning.