The immediate result was a 6 percent increase in beer prices and the end of a decades-long decline in real beer prices. Drinkers began paying almost $2 billion a year more for their beer. At least 5,000 Americans lost their jobs, and cost cutting followed, saving the new owners an estimated $2 billion. That money goes to those two conglomerates that have been able to reduce their tax bills and move much of their profits offshore.

This brewer’s duopoly has led to a second consolidation: wholesalers, the crucial intermediaries who distribute our beers to retailers. In 1980, there were 4,600 wholesalers in the country, and most markets had four or five competing wholesalers. Today, fewer than 3,000 remain, and in most local markets over 90 percent of the beer is controlled by distributors for these same two companies — one of which is dependent on AB InBev for most of its volume, and the other on Miller Coors.

These distributors are free to favor their primary suppliers over independent craft brewers when it comes to promotion, visibility, shelf space and marketing support. Laws passed in the 1970s to protect small “mom and pop” wholesalers from the big brewers are now obsolete and have the unintended consequence of creating an unfavorable balance of power — unfavorable to craft brewers and people who enjoy their beers.

The Department of Justice is allowing the damage to continue by greenlighting these two big brewers to extend their duopoly into craft beer by acquiring craft brewers. For example, in December the department approved AB InBev’s acquisition of Karbach, one of the largest craft brewers in Texas, a state where AB InBev already controls 52 percent of the beer market. Drinkers buying cute-sounding brands like Goose Island or Terrapin or Ten Barrel are often unaware that these brands, some of them once independent, are now just subsidiaries of AB InBev or Molson Coors, which are not transparent about disclosing their true ownership anywhere on the bottle.

This unwillingness to use effective antitrust enforcement to protect American economic interests is in stark contrast to how the rest of the world operates. Before approving AB InBev’s latest merger, antitrust authorities in China required it to sell its $1.6 billion stake in China’s largest brewer back to the Chinese government at a bargain-basement price. South Africa required guarantees of lifetime employment for its citizens, and the Monopolies Commission in the European Union required divestitures by SABMiller and AB InBev to keep their new, combined market share to 9 percent.