Pervasive trade barriers effectively force people to use inferior building blocks for their life. Trade barriers are an attempt by politicians to control the market. And politicians cannot control the market without commanding everyone who must rely on that market. If the government prohibited Americans from corresponding with citizens in the rest of the world, no one would deny that citizens' liberties had been trampled. The Soviet Union sought to protect the ruling class from competition from political ideas from abroad, while the United States sought to protect politically dominant industries from competition from foreign products.
Freedom of choice is as important in how one lives as in what one reads.
Either the government has a valid moral reason for restricting one citizen's freedom in order to boost another citizen's profits, or a trade barrier is unjust. In trade policy, government cannot pick winners without turning everyone else into losers. Every trade barrier constitutes a moral judgment that certain groups of producers, workers, and shareholders will be treated as superior to the rest of society. The government protects the steel industry by sacrificing precision metal makers and agricultural equipment exporters. The government protects 11,000 sugar growers by sacrificing the sugar refining and food manufacturing industries.