From the Federal Register:
The U.S. Copyright Office is issuing a notice of proposed rulemaking regarding the procedures for libraries and archives to opt out of proceedings before the Copyright Claims Board (“CCB”) and the procedures for a party before the CCB with respect to a class action proceeding, under the Copyright Alternative in Small-Claims Enforcement Act of 2020. The Office invites public comments on this proposed rule.
Comments on the proposed rule must be made in writing and received by the U.S. Copyright Office no later than 11:59 p.m. EDT on October 4, 2021.
The Copyright Alternative in Small-Claims Enforcement (“CASE”) Act of 2020  directs the Copyright Office to establish the Copyright Claims Board (“CCB” or “Board”), a voluntary tribunal within the Office comprised of three Copyright Claims Officers who have the authority to render determinations on certain copyright disputes with a low economic value.
Library and Archives Opt Out
The CASE Act directs the Register of Copyrights to “establish regulations allowing for a library or archives that does not wish to participate in proceedings before the Copyright Claims Board to preemptively opt out of such proceedings.”  The Office must also “compile and maintain a publicly available list of the libraries and archives that have successfully opted out of proceedings.”  In promulgating these regulations, the Register cannot “charge a library or archives a fee to preemptively opt out of proceedings” or “require a library or archives to renew a decision to preemptively opt out of proceedings.” 
Read the Full Text of the Proposed Rule