With some difficulty as things stand, although by signing a contract in advance each individual will be providing consent. But the technology exists and is already in use elsewhere that would allow each fan to be identified and carefully monitored for the duration of the event. It's not about how it will be policed, it'll be whether the state has the balls to mass prosecute. That would be risky until other technology arrives that will automatically apply social penalties to an individual's credit score, I understand we'll be calling it an "equity" score over here to avoid nasty associations with China.