adoptee's access to obc  is subject to a contact or disclosure veto

as of January 1, 2008, adult adoptees have unrestricted access to their original
birth certificates but may be subjected to a contact veto (and pay a hefty fine
if they violate it) in one state:

Tennessee (passive registry for birth parents; disclosure veto for rape victims) AD AP BP

adult adoptees have unrestricted access to their original birth certificates if the birth
parents have not filed a disclosure veto in one state:

Delaware (active registry) AD AP BP

in ten states, adult adoptees born or after a particular year (in parentheses)
may access their original birth certificates if their birth parents have not
filed a disclosure veto:

Colorado (post 1999) AD AP

Hawaii (post 1991) AD AP

Indiana (post 1993) AD AP BS

Michigan (pre 1945, post 1980) AD AP BP BS

Minnesota (post 1982) AD AP BP

Montana (post 1997) AD AP BP

Ohio (post 1996) AD AP

Oklahoma (post 1997) AD AP BP

Vermont (post 1986; waiver pre 1986) AD AP BP

Washington (post 1993) AD AP BP

in one state, adoptees over the age of 25  may access their orginal birth
certificate if the birth parents have not filed a disclosure veto:

Nebraska (waiver) AD AP

states which offer a mutual consent registry are listed in color

states which provide non-identifying information to adoptees
are marked with the abbreviation AD

states which provide non-identifying information to adoptive parents
are marked with the abbreviation AP

states which provide non-identifying information to birth parents
are marked with the abbreviation BP

states which provide non-identifying information to birth parents
are marked with the abbreviation BS