Idaho Code § 44-2003: Freedom of choice guaranteed, discrimination prohibited.

No person shall be required, as a condition of employment or continuation of employment, (1) to resign or refrain from voluntary membership in, voluntary affiliation with, or voluntary financial support of a labor organization, or, (2) to become or remain a member of a labor organization, or, (3) to pay any dues, fees, assessments, or other charges of any kind or amount to a labor organization, or, (4) to pay to any charity or other third party, in lieu of such payments, any amount equivalent to or a pro-rata portion of dues, fees, assessments, or other charges regularly required of members of a labor organization, or, (5) to be recommended, approved, referred, or cleared by or through a labor organization.