Professional License in State 
Is Not Always Necessary for an Expert to Testify

Most state courts which have considered the question have come to the legal conclusion that a testifying expert on a professional subject is not required to have a license from the state certifying authority before he/she can testify. We have a separate page noting cases in Arizona, Arkansas, Colorado, Iowa, Indiana, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Tennessee, Texas, Utah, Wisconsin, and Wyoming.. Go to that page for more specific information regarding those specific states.

"The prevailing view appears to be that education, training, knowledge, and experience in a given field are the factors that render a witness competent to testify as an expert and qualified to give an opinion on a subject within the scope of his or her expertise, rather than licensing by the state of the forum. In other words, it is not essential that an expert witness have a license and an expert witness is not rendered incompetent to give expert testimony simply on the ground that he or she is not registered nor conducts any practice in a particular state."

31A Am. Jur. 2d, Expert and Opinion Evidence at 50 (Footnotes omitted) (emphasis supplied).

Federal Court Practice Tip.  In the federal district courts a lawyer may practice law in the federal court even if not licensed to practice in the state in which the federal district lies. Hence it is possible to be licensed to practice law in the federal courts of the state but not in the state itself.  Expert attorneys may be licensed in the federal court but not in the state court involved. There is even authority that they may even have an office in the state if the office is limited to the federal court practice. 

"Once it is determined that there is a conflict between a valid federal law and a state law, the state law must give way....The Office of Disciplinary Counsel cannot point to any authority indicating that a federal court's power to determine who may practice law before it depends on the type of cases a lawyer intends to practice. Under 28 U.S.C. §§ 1654 & 2071 and the local rules, the Eastern District of Pennsylvania has the authority to determine who may practice law before it regardless of the extent to which a lawyer's practice might involve questions of state law. We therefore reject the argument that the intertwining of state and federal law somehow "preclude[s] a finding of federal preemption."

Surrick v. Killion, 449 F.3d 520 (3d Cir. 06/02/2006)

See also Opinion 17-06 of the Unauthorized Practice of Law Committee of the U.S. Court of Appeals for the District of Columbia Circuit, and Opinion 210 of the Virginia State Bar. But contra, Pennsylvania  Office of Disciplinary Counsel v. Marcone, 855 A. 2d 654 (2004).