A congressman vowed to renew his efforts to outlaw insider trading by Capitol Hill members and their staffs, following a Wall Street Journal investigation showing that congressional aides traded in companies overseen by their bosses.

Rep. Brian Baird (D., Wash.) and a handful of other lawmakers including Rep. Louise Slaughter (D., N.Y.) have for years supported legislation that would explicitly make it illegal for members and their aides to trade stocks and other securities based on non-public information gleaned...