A judge has been asked to settle the long-running controversy over whether Northern Ireland's second city should be called Londonderry or Derry.
The council wants to change the city's name to Derry
Mr Justice Weatherup is hearing a judicial review on the issue brought by Derry City Council.
The council wants the government to accept the council's view that the name of the city is Derry, not Londonerry.
The Department of the Environment has suggested such a change to the name would need a petition to the Sovereign.
Londonderry was established in a Royal Charter granted by King James I in 1613.
In 1984 the name of the nationalist-controlled council was changed from Londonderry to Derry, but the city itself continues to be officially known as Londonderry.
Unionists have opposed dropping the London prefix and claimed it would lead to further alienation in the city, which has a nationalist majority.
Michael Lavery, QC, said the council's view was that the Royal charters establishing the city had been amended by, and were subject to, the provisions of local government legislation.
"Consequently," he said, "when the name of the council changed to Derry in 1984 the name of the city established by charter changed and therefore it is unnecessary to petition the Sovereign in order to do so."
Bernard McCloskey, QC, for the DoE, said there was no government policy position or preference with regard to the correct title and he said it was questionable whether the council had made out a case for any change.
As well as seeking a declaration to change the city's name, the council has an alternative application which requires the respondents - the government and the DoE - to "take all reasonable steps to bring about the change to Derry and to facilitate the exercise of the Royal Prerogative if necessary".
Titles like 'maiden city', (despite a siege its defences were never breached) 'Foyle', (after the river which runs through it) and 'stroke city', (from Derry/Londonderry) have all been used by people trying to avoid controversy.
The name Derry is an Anglicisation of the original Gaelic name of the city, Doire, meaning oak grove.
The London prefix was added in 1613 when the city was granted a Royal Charter by King James I to reflect the association with the City of London and in particular The Honourable The Irish Society which had been granted lands in and around the city.
The hearing has been adjourned until Thursday when Mr Justice Weatherup is expected to reserve his decision.