Food and drink producers in the U.S. must state whether or not their products contain caffeine, but they are not required to disclose the exact amount, nor do they have to warn consumers that products that are typically caffeinated contain caffeine. This loophole applies to coffee, even decaf varieties, which can be confusing for consumers.

For coffee to be labeled as decaf, the FDA says that 97% of the caffeine must be removed, so most decaf coffee does have trace amounts of caffeine. Since some coffee beans have more or less caffeine than others, "97%" also represents a different amount for each product, and there's no rule about the maximum level of caffeine allowed in decaf.