The Supreme Court has backed a multibillion-dollar oil railroad expansion in Utah in a ruling that scales back a key environmental law and could speed development projects around the country.

Though the case centered on the Uinta Basin Railway, the Supreme Court’s decision could limit the scope of environmental reviews that federal agencies are legally required to conduct.

WASHINGTON — The Supreme Court backed a multibillion-dollar oil railroad expansion proposal in Utah on Thursday in a ruling that scales back the use of a key environmental law and could accelerate development projects around the country.