The fate of up to 13 ageing US warships destined for the UK for recycling is set to be decided in the courts. BBC News Online looks at the key issues.
What is the controversy about?
Environmentalists and official bodies are challenging plans to let up to 13 contaminated old US warships dock in the UK for dismantling and recycling.
They say the yard, owned by Able UK, on Teesside, does not have the requisite licences and permissions to do the work and fear an environmental disaster.
Able UK, which has a $16m (£10m) contract to process the so-called ghost ships, says it does have permission and the risks are no worse than for any other vessel.
What are the principal dangers?
The ships are up to 60 years old and are said to be fragile and at risk of breaking up, sparking pollution fears.
They contain a range of toxic materials, including lead, mercury, asbestos and polychlorinated biphenyls (PCBs), which have been linked to cancer and other health conditions.
Conservationists fear nearby wildlife sites are threatened by possible leaks.
But the Environment Agency says risks are low - if the facilities are safe.
What is the legal position?
Complex, to say the least. A High Court injunction bans any work on the ships until a full legal hearing in December.
But the UK government is powerless to stop the vessels entering British waters, and the first ships have already arrived.
The legality of working on foreign hazardous waste in the UK is one of the issues to be determined in the courts.
Able UK argues that existing approvals enable it to carry out the work, but the dock's suitability remains an issue.
Why is US toxic waste coming to the UK?
An American subsidiary of Able UK won the contract to recycle 13 of the obsolete ships, and chose to carry out the work at Able's Hartlepool shipyard.
Environmental campaigners say the US has the technology to do the work.
But the UK's Environment Agency initially agreed to the transfer on the basis that all approvals were in place.
A court will consider whether laws on overseas shipments have been breached.
So what happens now?
December's High Court hearing is the key, although the authorities appear to be prepared to compromise in the short term, allowing the first ships to dock at Teesside.
The UK government says legally the ships should go back to the US, but it admits their immediate return is impracticable, not least because of the risks posed by the weather, and nowhere else can take them safely at short notice.
Able UK is confident it has the rights to process them, but an injunction prevents any work until the hearing, leaving the ships in no man's land.
Oils and oily ballast water could cause damage to the marine environment.
Asbestos is a known carcinogen but is denser than water and non-soluble so would only pose a problem if blown on shore.
PCBs have been called a "probable carcinogen" and have been linked with neurological and developmental problems in humans.
Mercury, lead, chromium and cadmium are highly toxic metals which accumulate in the body.