Three abortion opponents who said they were offering silent prayers and not protesting out the front of Canberra's abortion clinic have had their charges dismissed.

In February last year, Kerry Mellor, John Popplewell and Ken Clancy — all aged in their 70s — were outside the city-based clinic.

The men, who oppose abortion, said they were there to silently pray.

In 2016, the ACT Legislative Assembly passed legislation that banned protesting in an exclusion zone around the abortion clinic in the city.

The ACT Government hoped the exclusion zone would stop protestors gathering at the clinic and causing distress to women entering the building.

The trio was charged by police for being in a protected area and engaging in prohibited behaviour.

They were each issued a $750 fine but, when they refused to pay, the matter moved to the ACT Magistrates Court.

The court heard the men were walking around the building silently praying and one sat on a nearby bench holding a pair of rosary beads.

Magistrate Glenn Theakston said the men did not communicate their message outwardly. ( Supplied )

The law prohibits "protest by any means" in the exclusion zone and the prosecution argued that the men's actions amounted to a protest.

Magistrate Glenn Theakston disagreed.

"They simply do not stand out as participating in any extraordinary activity. They do not even gather," his decision stated.

"I make these observations cognisant of their previous involvement in prayer vigils and their admitted views about abortion."

Magistrate Theakston dismissed the charges.

"I accept they were each engaged in silent prayer, and that such prayer involved no component of expression, communication or message to those around them," he said.

"The only reservation I have in that regard, arises from the presence of the rosary beads in the hands of Mr Clancy.

"However, the presence of those rosary beads, without any other symbolic display or gesture, leaves me with a significant doubt about whether there was any expression, communication or message by Mr Clancy."

Outside of court Mr Mellor said he stood by his actions.

"The charges have been dismissed, so the situation now is as long as we don't break the law in the future, and we always contended we didn't break it in the past, we're free to do the things we believe in and continue offering our prayers," he said.