THE US Supreme Court on Thursday struck down affirmative action in college admissions, declaring that race cannot be a factor.

The ruling forces institutions of higher education to look for new ways to achieve diverse student bodies.

The court's conservative majority effectively overturned cases reaching back 45 years in invalidating admissions plans at the universities of Harvard and North Carolina, the nation’s oldest private and public colleges respectively.

The decision, like last year's momentous abortion ruling that overturned Roe v Wade, marked the realisation of a long-sought conservative legal goal, this time finding that race-conscious admissions plans violate the constitution and a law that applies to colleges that receive federal funding, as almost all do.

Those schools will be forced to reshape their admissions practices, especially top schools that are more likely to consider the race of applicants.

Chief Justice John Roberts said that for too long universities have “concluded, wrongly, that the touchstone of an individual's identity is not challenges bested, skills built, or lessons learned but the colour of their skin. Our constitutional history does not tolerate that choice.”

From the White House, President Joe Biden said he “strongly, strongly” disagreed with the court’s ruling and urged colleges to seek other routes to diversity rather than let the ruling “be the last word.”

Besides the conservative-liberal split, the fight over affirmative action showed the deep gulf between the three justices of colour, each of whom wrote separately and vividly about race in the US and where the decision might lead.

The US’s second ever black justice, Clarence Thomas, who had long called for an end to affirmative action, wrote that the decision “sees the universities’ admissions policies for what they are: rudderless, race-based preferences designed to ensure a particular racial mix in their entering classes.”

Justice Sonia Sotomayor, the court’s first Latina, wrote in dissent that the decision “rolls back decades of precedent and momentous progress.”

In a separate dissent, Justice Ketanji Brown Jackson — the court’s first black female justice — called the decision “truly a tragedy for us all.”

Ms Jackson, who sat out the Harvard case because she had been a member of an advisory governing board, wrote: “With let-them-eat-cake obliviousness, today, the majority pulls the ripcord and announces ‘colorblindness for all’ by legal fiat. 

“But deeming race irrelevant in law does not make it so in life.”