A local authority has begun High Court proceedings in an attempt to halt council mergers in Dorset.
Christchurch Borough Council formally opposed plans to replace the county's nine councils with two unitary authorities earlier this month.
In a letter to the council, the government described the authority's bid as "absurd".
Christchurch said it had taken legal advice and had "an arguable case against the Secretary of State".
Under the plans, all nine councils would cease to exist and Bournemouth, Poole and Christchurch would merge.
A second council would be formed from Dorset County Council, East Dorset, North Dorset, Purbeck, Weymouth & Portland and West Dorset.
Christchurch Borough Council told the government it had acted "beyond its powers" in laying the changes before Parliament in March.
David Flagg, leader of the council, said: "Since the regulations have been laid in Parliament, the advice we have received is that the council has an arguable case against the Secretary of State.
"The opinion of our legal team, following the response we received last week, has not changed and, therefore, it is important that we ask the courts to review the decision."
He added: "We firmly believe that the regulations drafted by the Secretary of State are beyond his powers."
A spokesman for the Ministry of Housing, Communities & Local Government said: "As this is an on-going legal matter, it would not be appropriate to comment further."
Supporters of the changes, due to come into effect in April 2019, said they could save £108m over six years.
Christchurch Borough Council will now wait for a judge to make a decision about whether the judicial review should be heard in the High Court.
The council has declined to give the BBC any figures over its legal costs.