I think you are confusing two very different things, policy and law.
A law is drafted by parties who have an interest in its content. If a constitutionally (and politically) competent legislator can be persuaded to bring it forward, the law is proposed to whatever body is constitutionally charged with legislation. That body considers the law, debates and often amends its provisions, and ultimately (there may be further constitutional hoops to jump through) enacts it. Upon enactment, the law takes effect: becomes binding upon all citizens and corporations which fall under its provisions. It now falls to the executive and judicial authorities (supposing these to be entities distinct from the legislature) to implement the law: to put it into practical effect through public exercise of the public powers these authorities wield.
A policy need undergo none of these events, because a policy is not a law; it is merely a principle adopted by some entity as an appropriate guide to its subsequent actions. A policy may be embodied in a written statement, or it may be an entirely tacit and even unconscious assumption. It may be published and trumpeted, or maintained surreptitiously. It requires no formal enactment beyond the assent of those who agree to be governed by it, it is binding upon no-one at all (including those who adopt it), and it cannot be enforced or implemented except by extra-constitutional means, taking effect on whatever occasion, to whatever extent, and by whatever means, its adopters choose.