Environmental groups may have to wait months for a ruling on whether more so-called ghost ships can come to the UK.
About 100 vessels are awaiting disposal in the James River
A US court began hearing arguments on Friday as to whether the American government can send more former naval vessels to Teesside to be scrapped.
Four of the ships are already docked at Hartlepool-based Able UK, awaiting permission for break-up work to begin.
But the pressure group which launched the legal challenge said it could be months before a final decision.
On Friday the US Department of Transportation Maritime Administration (Marad) began putting its case for sending more vessels to the UK.
Able UK originally signed a deal to dismantle 13 ships at a dry dock facility in Hartlepool.
But a catalogue of planning and legal hurdles has delayed the remaining nine vessels, currently moored in the James River in Virginia, from leaving for the UK.
The US government wants to substitute the outstanding nine vessels for others, which it claims have lower levels or no PCBs at all.
Four of the vessels are currently moored in Hartlepool
The case, brought by the environmental pressure group Basal Action Network (Ban) began before a district judge in Washington DC.
The group has accused the US government of ignoring strict rules on exporting PCBs from the United States.
But Marad has insisted that no further ships will be allowed to sail to Teesside until Able UK has all the necessary permits and agreements with government agencies and Hartlepool Borough Council.
Able UK says it is in the process of submitting a renewed planning application for a dry dock to Hartlepool Council.
The company says it wants to establish a £30m a year business on Teesside, which could generate at least 200 new jobs.
A spokesman for Ban said: "Rather than address issues of serious concern with respect to exporting toxics ships, the government spent a great deal of the court's time questioning Ban's corporate structure in an attempt to try to disqualify the standing of our member organizations in the UK and in Virginia.
"It is clear the government does not want substantive matters discussed but would rather we be silenced through a legal technicality.
"The judge will decide in a matter of days, weeks or months on the matter before the court. She did not rule from the bench at this time."
No-one from Marad was available for comment.