If this is an an industry wide problem. You may want to take a look at various approaches to reader reliability testing. This is usually applied when collusion is not a fear. However, if you can identify some socially/geographically separate groups of judges, it may be possible to test whether judges that didn't know the athletes or their rankings would provide similar scores. If tape of the performance could be provided to an "independent" pool of judges and the new pool of judges was kept as blind to any additional information, then you could test if the two groups of judges returned similar scores. This would not be evidence of collusion. There could be regional differences between judges that could account for observed differences.

I know some NCAA judged sports (especially those judged by the coaches themselves) require a review of tape by a national committee before scores are excepted for entry into national level completion.

If this is an an industry wide problem. You may want to take a look at various approaches to reader reliability testing. This is usually applied when collusion is not a fear. However, if you can identify some socially/geographically separate groups of judges, it may be possible to test whether judges that didn't know the athletes or their rankings would provide similar scores. If tape of the performance could be provided to an "independent" pool of judges and the new pool of judges was kept as blind to any additional information, then you could test if the two groups of judges returned similar scores. This would not be evidence of collusion. There could be regional differences between judges that could account for observed differences.

I know some NCAA judged sports (especially those judged by the coaches themselves) require a review of tape by a national committee before scores are excepted for entry into national level competition.