The Supreme Court on Friday killed off a judicial doctrine that has protected many federal regulations from legal challenges for decades — delivering a major victory for conservatives and business groups seeking to curb the power of the executive branch.

The 6-3 decision divided the court along ideological lines. Its fallout will make it harder for President Joe Biden or any future president to act on a vast array of policy areas, from wiping out student debt and expanding protections for pregnant workers to curbing climate pollution and regulating artificial intelligence.

Known as Chevron deference, the Reagan-era doctrine required judges to defer to agencies’ “reasonable” interpretations of “ambiguous” federal laws. Now, judges will be freer to impose their own readings of the law — giving them broad leeway to upend regulations on health care, the environment, financial regulations, technology and more.