Even though it could idle some lawyers, partners from Baker Botts, Jackson Walker and Haynes and Boone—all Texas-based firms with corporate oil and gas clients—voiced tentative support this week for legislation that would tax carbon emissions while gutting environmental regulation.

They were reacting to news that ExxonMobil, Shell and BP had decided to back a carbon tax proposal outlined earlier this year by a coalition led by former Secretary of State James Baker. The energy companies published an ad in The Wall Street Journal this week to announce their support for Baker’s carbon tax ideas.