Many years ago the powers that be in the USCF went into agreement with a publishing company, giving them exclusive rights to the rules of the game (and all of the related standards, policies and procedures) as codified by US Chess. Which meant a Tournament Director (or any active player wanting to avoid issues) had to purchase the rule book – it was not available online.
Many members complained, but the contract was apparently very long term (if not forever). Until recently, when an amendment to the contract was put in place, allowing US Chess to publish selected chapters of the rule book (the ones most people are most interested in) online, for free.
You can view, search, and download these sections – CLICK HERE