The MIB, which is funded by an industry-wide levy on insurers and compensates victims of negligent uninsured drivers, is refusing to pay "a significant number of current and historic claims" from Helphire.
Helphire is attempting to recover £5.3 million from MIB to cover cases where its clients were provided with fake insurance details by the at-fault motorist.
But MIB is refusing to pay, arguing that it is not liable for the claims.
The case has already progressed to the Court of Appeal, and a judgement is expected soon.
However, Helphire has already obtained an order from a judge referring a test case to the European Court of Justice.