Wash. Rev. Code § 18.74.125
Nothing in this chapter shall prohibit any person licensed in this state under any other act from engaging in the practice for which he or she is licensed. Nothing in this chapter shall prohibit any person who, at any time prior to January 1, 1961, was practicing any healing or manipulative art in the state of Washington and designating the same as physical therapy or physiotherapy, from continuing to do so after the passage of this amendatory act: PROVIDED, That no such person shall represent himself or herself as being registered and shall not use in connection with his or her name the words or letters "registered" or "licensed" or "R.P.T."
RCW 18.74.125
Reviser's note: The language "after the passage of this amendatory act" refers to chapter 64, Laws of 1961 which passed the House March 1, 1961, passed the Senate February 27, 1961, approved by the governor March 6, 1961, and became effective at midnight June 7, 1961.