The bankruptcy sale of most of the assets of Dean Foods to Dairy Farmers of America will be litigated at least a little while longer.

A federal lawsuit filed last week by the Maryland and Virginia Milk Producers Cooperative Association and the Food Lion grocery chain asks that the sale be invalidated, and in particular that DFA be prohibited from acquiring at least one of three Dean facilities in North and South Carolina.

In its opening, the lawsuit alleges a “longstanding effort to seize control of the milk supply chain” by DFA, which it calls “the Standard Oil of the modern dairy industry.” DFA’s acquisition of 44 Dean plants in a bankruptcy sale will cement its dominance, the suit alleges.

The lawsuit is the latest salvo in a long-running war between DFA and other co-ops and independent dairy farmers. However, it comes in the wake of the U.S. Justice Department’s approval of the Dean bankruptcy sale.