But Benjamin Mark Sarlija was acquitted of possessing a prohibited weapon after police said they found the drugs and a knuckle duster inside his vehicle last year.

Sarlija pleaded not guilty to drug trafficking and illegal weapon offences in the ACT Magistrates Court and was committed to the higher court for trial.

Police said Sarlija seemed nervous because his hands shook, he looked down and stuttered when they stopped his car on Ginninderra Drive not far from his Lyneham home shortly before 11pm on June 14.

Court documents said they found rubbish and children's toys strewn throughout the back of the car when they searched it.

They also allegedly found a knuckle duster in the side compartment of the driver's door.

A police officer who discovered a brown paper McDonald's takeaway bag on the front passenger seat of the car emptied it out to find several empty burger wrappers and a wrapped burger.

He also found two golf ball-sized objects covered in grey-coloured electrical tape and a brown substance he initially thought was faecal matter.

Sarlija was charged after the police officer cut through the tape and a layer of plastic to find 14 grams of a white powder which tests later revealed was heroin.

Chief Justice Helen Murrell found Sarlija guilty of drug trafficking, but not guilty to possessing a prohibited weapon after a judge-only trial in the ACT Supreme Court last week.

In handing down his decision, Mr Mossop could not be satisfied beyond reasonable doubt that Sarlija knew the knuckle duster was inside the car and said there was little to link the weapon to the accused.

But he said the amount of heroin, which was almost three times the minimum trafficable quantity of 5 grams, was substantial and it would have been worth a significant amount of money.

He was satisfied beyond reasonable doubt that Sarlija had possessed the balls voluntarily and knew they contained an illegal drug.

Sarlija will be sentenced at a later date.