Blood Alcohol Content is the legal name for BAC but Blood Alcohol Concentration is sometimes used for simpler description. Blood alcohol content is usually expressed as a percentage of ethanol in the blood in units of mass of alcohol per volume of blood or mass of alcohol per mass of blood, depending on the country.
One way that society controls science is that the government can make certain experiments illegal. Hmm, maybe, but the apex answer is: People pass laws to restrict some research.
In the communist society that Marx described, the government has supreme authority through its total control of land and means of production. Because the government distributes land and property among the people, communism sets a standard of equality -- both economically and socially -- among its followers.