Imported milk protein has, once again, become a hot button in the U.S. dairy industry. The current controversy concerns Milk Protein Concentrate (MPC). Imports of MPC, a relatively new form of concentrated dairy-based protein, increased rapidly in the late 1990s, leading to charges that dairy farmers were being economically penalized. Bills were introduced in both the U.S. House and Senate in 2001 to restrict imports through the application of over-quota tariffs. A Senate bill to require special labeling of products manufactured from imported MPC has already been introduced in the 108th Congress.