Mr Scargill, 74, was given funding for the three-bedroom Barbican flat in 1982 when he was elected president of the National Union of Mineworkers.
But Mr Scargill who stepped down from his position 10 years ago wants the agreement to continue until his death which he says is in keeping with union tradition.
Chris Kitchen, NUM national secretary, the union is anxious to clarify the position. '"It has cost us a lot of money thus far and Arthur's family has a history of longevity. We can't lose at court - we will come out with a decision."
He admitted the continuing legal argument was costly but said it was worthwhile given the cost of paying £35,000 a year for the flat.
"It is a cost for the union which is struggling. We are not looking to evict Arthur from the flat or embarrass him."
The case will be heard in the Chancery Division in London.
• Trustees of the Yorkshire area NUM are appealing a court decision which granted Mr Scargill almost £13,500 in damages in a dispute over money towards a new car.
If mediation next month fails the case will go back to court in January.
Attempts by the Chronicle to contact Mr Scargill were unsuccessful.