TasPorts has admitted breaching competition law at Port Latta, but has avoided any penalty.
The state-owned ports company tried to hit miner Grange Resources Limited with a new port access charge after Grange said it would switch to using a private towage and pilotage services company, rather than use TasPorts' services.
Competition watchdog the ACCC started court proceedings in the Federal Court in 2019, alleging misconduct under the misuse of market power law.
It alleged TasPorts tried to stop Engage Marine effectively competing with TasPorts' marine pilotage and towage businesses, with the aim, effect and likely effect of lessening competition.
TasPorts in early 2020 said it denied the allegations and would vigorously defend them.
However, on Wednesday, TasPorts said as part of a settlement it had agreed to admit its conduct in relation to one allegation had the likely effect of substantially lessening competition.
That breach of the Competition and Consumer Act involved TasPorts imposing a new port access charge on Savage River iron ore miner Grange after the company said it was going to switch to Engage Marine Tasmania at its Port Latta export site.
The court made orders on Tuesday dismissing allegations TasPorts' conduct had the purpose or actual effect of substantially lessening competition.
The ACCC on Wednesday said TasPorts did not have a legal right to impose the new charge and sought to impose it without a full assessment of the cost of providing access services to Grange.
"There was a real commercial likelihood that if Grange agreed to pay the port charge, this would have the effect of raising Grange's future costs of acquiring services from Engage Marine," the ACCC said.
ACCC chair Rod Sims said it was an important decision because port services were pivotal for Tasmania's economy and it was the first time a corporation had been declared to have breached the revised misuse of market power law.
The ACCC said TasPorts had given it a court enforceable undertaking to ensure Engage Marine had access to berth space for tugboats at Inspection Head in the North on reasonable commercial terms and that charges for Grange for regulatory functions at Port Latta were reasonable.
The undertaking included TasPorts spending at least $1 million on wharf infrastructure at Inspection Head at Beauty Point.
The ACCC said it agreed not to press for a penalty order from the court in the circumstances.
"Accepting this consent outcome ensures towage customers in Northern Tasmania will receive the benefits form competition quickly," Mr Sims said.
"This competition should make a real difference at Tasmanian ports, ultimately to the benefit of consumers."
TasPorts chief executive Anthony Donald said the company was pleased to have resolved the case.
"TasPorts' focus, at all times, is maintaining the highest standards of maritime safety and environmental management in accordance with our regulatory obligations," he said.
TasPorts said the issues the ACCC raised "were complex, based on a unique set of circumstances and involved a previously untested provision of the Competition and Consumer Act".
Mr Donald said: "Tonnage charges for Port Latta are a unique legacy issue that dates back to the Marine Board of Hobart and Circular Head, prior to the formation of TasPorts in 2006."
"TasPorts is pleased to now move towards normalising those arrangements consistent with other ports around the state."
The resolution of the case followed mediation.