Who has the authority to enforce state and federal food labeling laws—the federal government, state regulators or the consumer? In early October, the US Supreme Court asked the Justice Department for advice on just such a question.

Supermarket chains, Kroger Co., SuperValu, Inc, and Safeway contend that only the government can own the responsibility for enforcing federal and state labeling laws. The question arose when the California Supreme Court cleared a consumer suit to move forward in the justice system. The suit claims that consumers were misled when they bought salmon containing astaxanthin and canthaxanthin, two chemicals used in salmon feed to give the fish's flesh its customary salmon color. FDA regulations allow their use as long as customers are notified. The claimants sued various grocery stores alleging the stores violated California's Sherman Law labeling requirements by selling artificially colored farmed salmon without labeling it as "color added" as required by law.

The grocery stores said in their appeal that the California ruling is an "open invitation" for private citizens to bring class action suits that will challenge enforcement rules as set by the Food, Drug and Cosmetic Act, which governs food labeling at the federal level and prevents private efforts to enforce similar state laws.

The high court's request, directed to U.S. Solicitor Gen. Gregory Garre, may be a sign that the justices will add the case to their 2008-09 docket.