Nick Griffin has been receiving treatment for kidney stones The battle between the equalities watchdog and the British National Party over the party’s membership policy returns to court on Monday.
The BNP voted on new rules after facing the threat of a court injunction over its “whites only” membership.
But the Equality and Human Rights said the new rules were still “indirectly discriminatory”.
BNP leader Nick Griffin has applied for the cases to be thrown out but is not at court as he is in hospital.
It is understood he is being treated for kidney stones.
BNP supporters and rival activists from Unite Against Fascism have been outside the Royal Courts of Justice ahead of the hearing.
The BBC’s Mike Sergeant said if the BNP lost the case, the equalities commission was likely to press for the party’s assets to be seized.
Earlier this year BNP members backed changes to the party’s constitution to allow “non-indigenous Britons” to join, after the Commission took legal action.
But the court has previously heard that prospective members still had to sign up to principles including a duty to oppose the promotion of any form of “integration or assimilation” that impacted on the “indigenous British”, and a requirement to support the “maintenance and existence of the unity and integrity of the indigenous British”.
The commission argues that the principles could be interpreted to oppose mixed marriages and could force people to deny their own identity. The BNP says the case is a politically motivated and a waste of public money.
In a statement, the BNP said: “Regardless of whether our chairman is fit to attend, our activists will be outside the court to protest against this taxpayer-funded assault on our freedom of association.
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