A lawyer for the owner of the Austrian house where Adolf Hitler was born is disputing the government's right to take possession of the property at the country's highest court.
Gerhard Lebitsch said authorities are using the measure "like a club" because his client, Gerlinde Pommer, refused purchase offers that were too low.
The challenge is in response to a government bill to take the house after Ms Pommer refused to sell it.
Hitler was born in 1889 in the house in Braunau am Inn, a town on the German border.
The government wants to remodel the property's facade to reduce its draw as a shrine for admirers of the Nazi dictator and to offer it to an agency that runs workshops for disabled people.
Ahead of the first day of Constitutional Court hearings, Mr Lebitsch questioned the timing of the government's move so long after the Second World War, noting that "they could have neutralised the site 40 to 50 years ago".
While the price offered by the state has not been disclosed, Mr Lebitsch suggested it was too low, describing the offer as "half-hearted".
In court, officials for the government argued that the state decided to seize the house after the owner refused to make alterations needed for use in workshops.
They also said the state was confronted with unjustified rent increases while leasing the building previously.