… is from pages 388-389 of the Definitive Edition (Ronald Hamowy, ed., 2011) of F.A. Hayek’s 1960 volume, The Constitution of Liberty:
It cannot be stressed enough that the coercion which unions have been permitted to exercise contrary to all principles of freedom under the law is primarily the coercion of fellow workers. Whatever true coercive power unions may be able to wield over employers is a consequence of this primary power of coercing other workers; the coercion of employers would lose most of its objectionable character if unions were deprived of this power to exact unwilling support….
[W]orkers can raise real wages above the level that would prevail on a free market only by limiting the supply, that is, by withholding part of labor. The interest of those who will get employment at the higher wage will therefore aways be opposed to the interest of those who, in consequence, will find employment only in the less highly paid jobs or who will not be employed at all.