ISKCON membership is defined by accepting ultimate authority of the GBC. What do you mean there are no referees?

ISKCON was an organization founded by Srila Prabhupada and everyone professing loyalty to ISKCON accept Prabhupada's authority. While the definition of ISKCON membership is accepting the authority of GBC, one could rightfully claim that GBC is fallen and an illegitimate referee its actions are viewed as being consistently corrupt after the passing of Prabhupada. However, this is a matter of perspective. Moreover, arguing semantics about the "definition of ISKCON membership" with respect to what I mentioned is completely fruitless. So let's accept your definition of ISKCON membership.

Even then, there is a great diversity of opinions within ISKCON that have not been resolved. Hanuman Das of Croatia is a commentator on YouTube who openly criticizes many prominent ISKCON leaders. This includes:

• Sacinananda Swami (Europe) for consorting closely with a female secretary.

• Radhanath Swami (Mumbai Chowpatty) for placing too much emphasis on mundane charitable endeavors

• and Hridayananda Goswami (Krishna West) for rejecting cultural norms that Prabhupada introduced.

I don't personally claim or disclaim that they are 100% valid, aspects of Hanuman Das's criticisms are certainly shared by large portions of the ISKCON membership (in your definition). This holds true even if Hanuman Das himself is officially barred from his local temples for his public criticisms.

The GBC officially views the three ISKCON leaders mentioned above as being legitimate. But the disagreements regarding their conduct or actions still exist within the main body of ISKCON. That is all I meant.