A recent Ohio Court of Appeals case brings out a problem with scientists establishing credentials in providing professional consulting services:

Schroeder v. State Board of Registration for Professional Engineers..........etc.
http://www.sconet.state.oh.us/rod/ newpdf/10/2004/2004-ohio-5793.pdf

This is a trend more recently noted in Texas.
http://www.sos.state.tx.us/texreg/archive/October292004/in-addition/in-addition.html#549
where the State Board of Engineers is proposing that non-engineers working in water related areas require supervision by a PE.