Alexander Scott Hagan, 52, pleaded guilty to three drug trafficking charges related to cocaine, MDMA, and a large commercial quantity of methylamphetamine, also known as ice, shortly before he was set to go on trial in the ACT Supreme Court this year.

ACT Policing said officers had seized the drugs from the boot and body work of the car when they searched a Volkswagen Passat after watching a man leave a Curtin property about 1.30pm on October 23, 2014.

Hagan, who has been behind bars for nearly two years, faced a sentencing hearing before Justice John Burns in court on Wednesday.

The court heard Hagan had packed the ice into his car at a friend's place and arranged for a third person to drive the hidden drugs from Canberra to a shopping centre in Melbourne.

Defence barrister James Lawton said Hagan had organised to transport the drugs because he owed money to two bikies, who he had refused to name, for cocaine.

Justice Burns suggested Hagan had money in two bank accounts which he could have used to pay off his drug debts, rather than get involved with the drug smuggling operation.

But Mr Lawton said Hagan feared retribution if he didn't do what the two associates asked - a circumstance he said didn't quite amount to a defence of duress but did go some way to explain the reasons which led to his offending.

"He wasn't particularly given a choice by the people organising the drug run," he said.

Mr Lawton argued Hagan was "a courier, arranging another courier to transport the drugs" and never had any intent of supplying ice or MDMA tablets the drug suppliers gave him.

He said Hagan began using cocaine in the year leading up to the operation and eventually ended up supplying the drug to "a very limited clientele" of four friends.

A pre-sentence report found Hagan, a father-of-three who ran his own business, was at low risk of reoffending and would need minimal supervision if he was released back into the community.

Crown prosecutor Shane Drumgold said Hagan hadn't been scared enough of the drug suppliers to jeopardise his business and had instead been willing to traffic the drugs to settle his debts.

He said general deterrence was paramount in sentencing Hagan, noting the 28-kilogram ice haul was equal to about 300,000 individual doses with a street value of many millions of dollars.

The 58 balls of cocaine police seized had an estimated street value of $50,000, while 936 MDMA pills were valued at nearly $30,000, he said.

Mr Drumgold argued any sentence needed to acknowledge the lives that could be destroyed by the scourge of those drugs and the wider negative impacts on the community.

It should also send a clear message to those involved in the wholesale drug trade that their crimes would attract a significant term of imprisonment, he said.

Justice Burns reserved his decision.