A Catch-22 faced by consumers seeking to change allegedly deceptive product labels took center stage at oral argument April 19 in the Ninth Circuit in a suit over Mott’s apple juice (Rahman v. Mott’s LLP, 9th Cir., No. 15-15579, argued 4/19/17).

Judges asked whether an informed purchaser may represent a class seeking label modifications.

Under the U.S. Constitution, a plaintiff has standing to seek injunctive relief if that would prevent future harm. But a label change wouldn’t benefit...