In an opinion issued last week the Kentucky Court of Appeals held that:Reading the plain language of the statutes, we believe the General Assembly meant only to prohibit an unlicensed individual from offering private investigation services to the public; hence, the prohibition against 'hold[ing oneself] out to the public as a private investigator[.]' Providing testimony in a court proceeding is not the equivalent of selling the public one’s services as a private detective. . . . Kentucky’s statutes governing the practice of private investigating are simply not meant to have any evidentiary effect, and to prohibit the testimony of Lukjan’s expert on that basis was erroneous.

So, no license required to testify—though perhaps you get in trouble with the authorities if you advertise to the public that you are available to do O&C work in Kentucky and are not licensed to do so." The case is also a good discussion of the Daubert procedural requirements in Kentucky.