Global Law Trials.
Law trials effective August 1 for 15s and, in the U.S., August 16 for 7s. USA memo (PDF): https://rsvsport.files.wordpress.com/2021/08/global-law-trials-2021.pdf
USA Eligibility Guidelines for 2021-2022
https://assets.usarugby.org/docs/club/2021-22-Eligibility-Regulations.pdf