There is a trend nationwide to require NCIDQ certification in order to aquire a state license. Since FIDER accreditation is required for NCIDQ, your wife's situation could be tricky.
More states are beginning to license interior designers as design professionals, such as architects and engineers. I their cases, licensure is critical, and I anticipate that it will become critical to interior design.
Check out
www.asid.org for more information on licensure. I'm sure that they have information there.
Ryan