Michigan Historical Collections (MHC) materials are typically open to the public unless the donor(s) have imposed specific access restrictions on them in a gift or deposit agreement. If such restrictions have been requested, then that material is generally restricted until December 31st of the year noted in the agreement.
In select cases, such as with congressional collections, specific regulations or statutes may require the processor to impose slightly different access restrictions. For example, in compliance with Senate Resolution 474, committee records are restricted for twenty (20) years from their date of creation (unless previously made public by the committee) while records related to an investigation--for example, the Permanent Subcommittee on Investigations (PSI)--as well as executive nominations are restricted for fifty (50) years from the date of creation.
Twice a year (shortly after January 1 and July 1), the Assistant Director for Collections Management reviews and unpublishes expired access restriction notes in ArchivesSpace.
For instructions on how to create access restrictions in a finding aid, consult the Common Archival Elements page of this site.