The Judges Course is recommended for everyone, but mandatory for only a small subset of all judges.
During the Open, only four groups of people must take the course:
1. Affiliate Managers
2. In-person judges of Games/Qualifier-caliber athletes
3. Online judges of video submissions
4. Judges who want to serve at the Games
Those who have passed the latest edition of the Judges Course are called registered judges. Similar to a CPR certificate, judges must review and re-test their skills regularly. CrossFit requires that judges take and pass the course each year.
*NOTE* The 2019 Judges Course will be valid for the 2020 Open which begins in October of 2019. If you've already completed the 2019 course you're all set and do not need to retake it.