SAN FRANCISCO — Retailers were stunned two years ago when the California Supreme Court ruled they broke a 1971 privacy law by requiring consumer ZIP codes to process credit card transactions.

On Wednesday, three e-commerce giants rushed into court, urging the court to clarify that the same law doesn’t apply to online credit card transactions, too. If e-tailers can’t use personal information to verify credit card user identity, “it will bring an end to online commerce,” Gibson, Dunn & Crutcher partner Daniel Kolkey told the justices.