What is this law? Years ago, when they built the D/FW airport, they wanted to make sure they routed all local traffic through that airport and strangled all the competitive airports. The Wright Amendment says that other local airports, particularly Dallas Love Field, can only have flights to Texas and adjoining states.
Well, this sounds just like a bit of municipal priority setting, until one other fact is thrown in. Love Field is Southwest Airlines home field. By placing this limitation on Love field, and keeping it that way, American Airlines and Delta get an effective subsidy, ensuring that they have no low-cost competition on their longer routes.
I lived in Dallas for years and trevelled far and wide by air. The Wright Ammendment cost me and my company at least $10,000 over that time in higher air fares.