Whether a group is a criminal organization is an element of the offence. It has to be proven by the crown beyond a reasonable doubt each and every time. Because it's an element of the offence, the way the charter works you can't simply apply one decision into another fact pattern currently. It's just the nature of our criminal process.
If there were reform in that area, for example, where a decision could be put before a court and then defence counsel could make submissions on it, that might be a way to assist in the process, but this happens because it's an element of the offence. It would be no different from being charged with a criminal offence: the crown couldn't rely on a conviction of another person to prove my guilt.