Mars, Inc. and its M&M’s Minis candy are the latest targets in a wave of “slack-fill” litigation.

Slack-fill is empty space in product packaging – i.e., the difference between the maximum capacity of a product’s container and the actual volume of product inside. Slack-fill litigation has increased in recent years as class plaintiffs allege that companies are deliberately including empty space in their packaging to deceive consumers into paying higher prices for lower product quantities.

In the recent putative class action involving M&M’s Minis, filed in the Eastern District of New York, the plaintiffs allege that the candy’s containers, plastic tubes available in two sizes, have as much as 14 and 22 percent slack-fill. The plaintiffs assert that consumers are unable to discover the empty space in the containers until after purchase because the tubes are opaque and covered with brightly-colored wrappings. Alleging various tort claims and unjust enrichment, the plaintiffs claim that Mars deceptively uses unnecessarily large packaging to maximize shelf presence over competitors and enable retailers to sell the candy at higher prices than other similar products.

Similar suits over slack-fill in recent years have involved products such as deodorant, laundry detergent, nutritional supplements and canned tuna. Although these class actions have been more commonly directed at manufacturers, retailers are also being targeted for allegedly selling private-label products with excessive and misleading slack-fill.

For example, Wal-Mart and other unnamed retailers are defendants in multidistrict litigation, originally filed in the Northern District of Illinois, concerning allegations of slack-fill. The plaintiffs in that case allege that the defendant retailers, who market and sell private-label brands of McCormick pepper, have been deceptively increasing their slack-fill in response to the rising price of black pepper. The complaint alleges that the defendants conspired to reduce the amount of pepper being sold, but continued using the same size tins they had been selling for many years.

Slack-fill litigation is unlikely to wane because there are few barriers to plaintiffs wanting to assert claims. Unlike other areas of consumer protection where regulations may vary significantly by state, slack-fill is largely regulated at the federal level. Federal law, which preempts conflicting state rules in this area, generally permits use of “functional” slack-fill but prohibits slack-fill that is undisclosed and determined to be nonfunctional (i.e., empty space that does not serve a purpose such as protecting the contents of the package). With the exception of California, which has its own prohibition on deceptive, nonfunctional slack-fill in commodity packaging, few other states appear to have their own supplementary regulations.

The upshot is that, as the wave of slack-fill litigation continues to rise, the plaintiffs’ bar largely has the advantage of forum shopping. And retailers should be mindful of areas in which they may be susceptible to increased exposure, particularly in the area of private-label products.