Washington (CNN) Deep in a seemingly obscure Supreme Court case on Monday, Justice Ruth Bader Ginsburg sounded an alarm for liberals: The New Deal may be under attack.

The conservative majority is undermining worker protections from the 1930s, Ginsburg wrote, "without even acknowledging that it unsettles more than half a century of our precedent."

In the 5-4 ruling along familiar ideological lines, the conservative majority disallowed overtime pay for automobile service advisers at a California Mercedes-Benz dealership by broadly construing a category of exemptions in the Fair Labor Standards Act for overtime protection.

Certainly, the subject of the decision -- the only one issued Monday as the court continues its notably sluggish pace -- pales compared with pending cases on religion and gay rights, partisan gerrymandering, and the Trump administration travel ban.

Yet the fair labor controversy offers a lens on a likely struggle among justices over the role of federal government in American life.

Read More