Colorado Revised Statutes Title 8. Labor and Industry § 8-3-109. What are not unfair labor practices

(1) It is not an unfair labor practice for any employer to refuse to grant a closed shop or all-union agreement or to accede to any proposal therefor as provided in this article.

(2) The right of both employer and employee freely to express, declare, and publish their respective views and proposals concerning any labor relationship shall not be abrogated or limited by this article, nor shall the exercise of such right constitute an unfair labor practice. No strike shall be lawful unless it is authorized by a majority vote of the employees in the union involved taken by secret ballot such as is provided in this article.

(3) It shall not be an unfair labor practice for an employer engaged primarily in the building and construction industry to enter into an all-union agreement, except an agreement providing for an agency shop or modified agency shop, with a labor organization, which agreement is limited in its coverage to employees who, upon their employment, will be engaged in the building and construction industry, if a copy of such agreement is filed with the director and certified by him as provided in section 8-3-108(1)(c)(II)(B). Such agreement may be ratified as provided in section 8-3-108(1)(c)(II)(C) or terminated by the director as provided in section 8-3-108(1)(c)(III).