Is Oregon the only state that disallows use of most unaccredited degrees?
No. It is also illegal or restricted in North Dakota, South Dakota, Illinois, Missouri, New Jersey, Texas, Nevada, Washington, Virginia and Maine to use unaccredited degrees. It is illegal in Indiana to use an unaccredited doctorate and Michigan law limits the legal options of users. See those states laws http://www.osac.state.or.us/oda/unaccredited.aspx for details. Many other states are considering similar laws in order to prevent fraud.