Westminster mistake making it illegal to possess eggs collected between 1954 and 1981 left museums at risk of prosecution

Weaknesses in parliament's law-making procedures have been exposed by a curious case encompassing a Tyneside egg-collector, the hatching of a non-existent offence, and the criminalisation of Britain's museums.

Seven years after a statutory instrument updating nature regulations glided virtually unobserved through Westminster, the Department for Environment, Food and Rural Affairs (Defra) has this week admitted it "unlawfully" put a new crime on the statute books.

The unintended outcome of the rarely deployed Wildlife & Countryside Act 1981 Amendment Regulations, Statutory Instrument (SI) 1487/2004, has been shot down by lawyers' persistent questioning.

Quincy Whitaker, a barrister at Doughty Street chambers, London, and Nigel Barnes, a solicitor at the Sunderland and Newcastle firm Ben Hoare Bell, realised that a parliamentary drafting error had accidentally removed a previous defence and laid in its place, cuckoo-like, a constitutionally impossible crime.

The regulations, meant to harmonise UK bird protection rules with EU laws, made illegal the possession of wild eggs collected from 1954-1981. Police and wildlife agencies used the new regulations to prosecute a number of people.

The change in the law was never the subject of public consultation, neither was it debated in parliament. The retrospective criminalisation of historic collections has caused museums, scientific research organisations and private collectors to the risk of prosecution.

One of the first people to discover the law had changed was John Dodsworth, 52, who has past wildlife convictions. His home was raided by the police wearing riot gear in 2006 and about 1,000 eggs were seized from there. "Officers used a battering ram to force their way in. The children were very upset to see their parents manhandled by the police."

At South Tyneside magistrates court three years later Dodsworth, an asbestos removal supervisor, pleaded guilty to one offence of possessing wild birds' eggs, but said: "I should never have been prosecuted.But when I was taken to court I was told it was a strict liability offence and I had to plead guilty. I was given a 100 hours community service order."

Helater decided to appeal against both conviction and sentence. The sentence ?was quashed in January 2010 and Dodsworth was granted an absolute discharge on the grounds that no one was aware such possession had been an offence at the time. "But they were still prosecuting people for this as recently as September," he said.

An overturn of the disputed section of SI 1487/2004 has proved more difficult.

Whitaker told the high court: "The retrospective criminalisation of possession of eggs that were lawfully held prior to the enactment of the regulations (those collected from 1954-1981) has widespread implications for museums and other public collections, natural history and scientific research collections and private egg collectors throughout Britain.

"[The creation of a new crime] would have been expected to have been widely announced and debated within the relevant communities if it was the intention that the regulations should have such an effect." Her judicial review case was also brought against the Crown Prosecution Service to prevent pursuit of fresh cases.

Evidence was given by Bob McGowan, senior curator of birds at the National Museum of Scotland, who said that the change in the law required him to assess 36,000 clutches of eggs in his collection. "It is difficult to imagine this particular outcome was an intention of the amendment," he said in a statement.

For several years after the law was changed the CPS website continued to advise that possessing historic eggs was legal, Whitaker added. The Royal Society for the Protection of Birds believes the change was a legislative error rather than intentional.

Nigel Barnes, who represented Dodsworth in his appeals against sentence and conviction, submitted a series of freedom of information requests. "I questioned whether the statutory instrument was lawful," he said. "What are the CPS going to do now about the people who have been convicted? It may be a handful, it may be more. There are many more who may have committed an offence without realising it."

Whitaker searched through the parliamentary papers and Defra files. "When I got the papers I realised it must have been a drafting error," Whitaker explained. "The department has now conceded it was wrong.

Whitaker said: "It's an example of how much modern-day legislation is passed by civil servants without anybody understanding it.

"Had anyone realised what had happened, it should have been referred to parliament because it creates a criminal offence. As it was, it was unconstitutional.

"The House of Lords had specifically rejected the creation of the offence which the amendment regulations in fact created when the original act (the Wildlife & Countryside Act 1981) was debated in parliament.

"To create an offence that was contrary to the express will of parliament by delegated legislation without informing anyone that it has that effect is highly unconstitutional to say the least."

A Defra spokesman confirmed that the department now accepted the change to the law was illegal.

A statement said: "The 2004 consultation documents on the draft statutory instrument did not outline an intention to remove the pre-1981 defence in relation to the possession of wild bird eggs. Defra has accepted that, as the consultation did not mention those particular changes, they were unlawfully made."