Persons licensed to practice chiropractic under the laws of any other state, territory of the United States, the District of Columbia, Puerto Rico, or province of Canada, having qualifications substantially equivalent to those required by this chapter, may, in the discretion of the commission, and after such examination as may be required by rule of the commission, be issued a license to practice in this state without further examination, upon payment of a fee determined by the secretary as provided in RCW 43.70.250.