The High Court is to hear arguments from Greenpeace that granting oil drilling licences in UK deep waters is illegal. Mr Justice Ouseley permitted a judicial review in late February.
Interest in oil exploration in deep waters west and north of the Shetlands is growing despite harsh weather, huge waves and the difficulty that drilling at depths of 300 metres poses.
Greenpeace is seeking to quash the award of a production licence there to Faroe Petroleum, granted by DECC on 4 October last year.
The campaigners want the court to declare that an appropriate assessment under the EU Habitats Directive is needed before oil exploration is permitted in waters over 300m deep. DECC decided this was unnecessary on 22 October.
Greenpeace also wants the deepwater exploration licences awarded that month to be declared illegal, because DECC did not wait for the outcome of the investigation into the causes of the Deepwater Horizon disaster in the Gulf of Mexico last summer. Reliance on a strategic environmental assessment done beforehand may also be deemed unlawful.
DECC has until 31 March to present its defence. Other oil companies, including Chevron, Eni, DONG and Faroe Petroleum may join in defending the case.
MPs rejected a deepwater drilling ban earlier this year, but called for better oil spill response plans (ENDS Report 432, pp 52-53).