Conservative and liberal U.S. Supreme Court justices on Tuesday appeared reluctant to broaden protections for corporate insiders who blow the whistle on securities law violations or fraud by their companies.

During an hour-long argument in the case, several justices signaled that they believed the 2010 Dodd-Frank Wall Street reform law at the center of the dispute does not protect those who report the violations only internally instead of to the U.S. Securities and Exchange Commission.

The case involves Digital Realty Trust Inc.'s appeal of a lower court ruling in favor of a fired executive, Paul Somers, after he complained internally about alleged misconduct by his supervisor but never reported the matter to the SEC.