Wash. Rev. Code § 81.68.040
An auto transportation company shall not operate for the transportation of persons and their baggage for compensation between fixed termini or over a regular route in this state, without first having obtained from the commission under this chapter a certificate declaring that public convenience and necessity require such operation. Any right, privilege, certificate held, owned, or obtained by an auto transportation company may be sold, assigned, leased, transferred, or inherited as other property, only if authorized by the commission. The commission may, after notice and an opportunity for a hearing, when the applicant requests a certificate to operate in a territory already served by a certificate holder under this chapter, only when the existing auto transportation company or companies serving such territory will not provide the same to the satisfaction of the commission, or when the existing auto transportation company does not object, and in all other cases with or without hearing, issue the certificate as prayed for; or for good cause shown, may refuse to issue same, or issue it for the partial exercise only of the privilege sought, and may attach to the exercise of the rights granted by the certificate to such terms and conditions as, in its judgment, the public convenience and necessity may require.
RCW 81.68.040