A proposal to auction off Eamon de Valera's presidential 1949 Rolls Royce Silver Wraith in 1976 resulted in the attorney general being asked for his opinion on whether the historic car was covered by the National Monuments Act.
A Department of Justice memo said a technical report indicated the Rolls Royce (registration ZJ 5000) was not suitable to be used as a State car as it was in need of "a general overhaul" and it was decided to dispose of it.
"The question has arisen whether the car could be regarded as coming within the definition of 'archaeological object'," the memo says.
If so that would mean the car could not be exported without a special licence from the minister for education.
It says the car was originally purchased for ceremonial occasions, but in practice was mainly used by the President.
After de Valera moved to the Arás an Uachtarain in 1959, it was used wholly by him.
"As he became increasingly feeble, it was found that the high dimensions of the Rolls facilitated his movement in and out of the car."
When he retired in 1973 he was allowed to continue to use the car until his death in 1975.
The attorney general said it had to be decided was de Valera "an historical person" and whether the value of the Rolls Royce would be inflated because of his association with it.
He said it could not be doubted that de Valera "played a significant role in the life of the country" but it was a matter of opinion whether his presidential years represented the most significant period of his career.
However, he said: ""If, for instance, one were offered Sarsfield's coat, one would not reject it merely because he had not worn it at Landen of Ballyneety."
He said Rolls Royces were coveted, and large sums were paid for vintage models.
In advance of a sale it could not be said with certainty "whether that value would be increased, and increased 'substantially', by reason of the car's long association with Mr de Valera".