IN 2012, John Roberts, America’s chief justice, angered conservatives when he formed a majority with his four liberal colleagues to save Obamacare from its first major legal attack. Three years on, in 2015, he did so again to uphold campaign-finance rules for judges. Later that spring, he and Justice Anthony Kennedy teamed up with the liberals to rebuff a second assault on Obamacare. On May 1st, the moderate side of Justice Roberts reappeared when he once again shuffled to the left to stand up to banks that had targeted racial minorities for subprime loans. But if a prediction in Justice Clarence Thomas’s partial dissent proves accurate, caveats in the majority opinion may seriously undermine the ostensible liberal victory.

In Bank of America v City of Miami, the Supreme Court considered whether Miami may attempt to recoup losses it suffered from the 2008 recession by suing Bank of America and Wells Fargo, two of America’s biggest banks, for extending low-cost loans to white people while selling black people and Latinos risky mortgages with high fees and inflated interest rates. Miami claimed that a decade of discriminatory lending contributed to segregation and led minority borrowers to miss payments and lose their homes. Foreclosures then depressed property values, bringing boarded-up windows and dangerous street corners. This spurred Miami to spend more on policing, fire protection and other city services while its tax base withered. The impact on the city’s finances, Miami claimed, made it an aggrieved party under the Fair Housing Act (FHA), a law passed in 1968 prohibiting racial discrimination in the lease, sale and financing of property.

At the oral argument on election day in November, only the four liberal justices seemed receptive to Miami’s claim. Justice Roberts and Justice Kennedy sounded unwilling to set a precedent that would allow cities to sue banks for millions of dollars whenever they could draw a line plausibly connecting the dots between a lending practice and a neighbourhood’s decline. The FHA, Justice Kennedy said, “doesn't prohibit decreasing property tax values”. Justice Roberts added, in colloquy with Miami’s lawyer, “I don't see how you can say that your loss of property taxes is a direct injury”. But in the end, Justice Kennedy sided with the banks while Justice Roberts joined Justice Stephen Breyer’s majority decision.

Justice Breyer’s workmanlike opinion has something for both sides. First, turning to Gladstone, Realtors v. Village of Bellwood (1979), he accepted Miami’s contention that cities are, under certain circumstances, eligible to sue for damages under the FHA. Miami, he wrote, “is an ‘aggrieved person’ able to bring suit under the statute”. Yet bringing a suit and winning it are two different things. “[T]o establish proximate cause under the FHA”, Justice Breyer held, “a plaintiff must do more than show that its injuries foreseeably flowed from the alleged statutory violation”. Proving damages in this context must be a matter of direct injury: absent a concrete harm flowing directly from the bank’s loan scheme, a city has no case. The Eleventh Circuit Court of Appeals held that “foreseeable” results from real-estate transactions are enough to permit a city to sue, but Justice Breyer found this standard too loose. There must be, he wrote, a “close connection”. Violating the FHA may “‘be expected to cause ripples of harm to flow’ far beyond the defendant’s misconduct”, he wrote, quoting a 1983 case. But opening up all such bad behaviour causing harm down the road to litigation is to turn the courts into the jurisprudential equivalent of “If You Give a Mouse a Cookie”, the children’s book trading on elaborate causal links between an initial move and a remote result. “Nothing in the statute”, Justice Breyer concluded, “suggests that Congress intended to provide a remedy wherever those ripples travel.”

Justice Samuel Alito was uncharacteristically silent during the Bank of America oral argument, while Justice Thomas was characteristically so. They, along with a more voluble Justice Kennedy, rejected Justice Breyer’s first contention in Monday’s ruling: “[N]othing in the text of the FHA suggests that Congress was concerned about decreased property values, foreclosures and urban blight, much less about strains on municipal budgets that might follow”, Justice Thomas wrote for his two colleagues. But the three agreed with Justice Breyer’s second point that only a direct injury would permit the city to show it had suffered at the hands of the banks’ discriminatory loans. For Justice Thomas, this standard of proof dooms Miami’s case: “[T]he majority opinion leaves little doubt that neither Miami nor any similarly situated plaintiff can satisfy the rigorous standard for proximate cause that the court adopts and leaves to the court of appeals to apply.” In other words, the invitation to cities to sue big banks comes with a giant asterisk: unless they can show predatory loans caused them direct harm, the FHA will be no good as a tool to win big settlements.

Trading on rumours that Justice Kennedy, 80, is pondering retirement, Rick Hasen, a noted Supreme Court observer at the University of California, Irvine, tweeted that Justice Roberts’s move in Bank of America shows he’s “practicing for when he will be the new swing justice”. There may be a simpler explanation for the chief’s rare jaunt to the liberal side of the bench. With only eight justices considering the case, a vote with his typical allies would have produced a 4-4 split. Justice Roberts has no love for ties; in public statements he frequently laments the court’s perceived politicisation and praises narrow rulings and compromise. And he may have good reason to avoid a tie in this case, as a split would have affirmed an Eleventh Circuit ruling permitting an expansive power for cities to sue banks under the Fair Housing Act. He may have offered his vote to the liberals in exchange for a more constrained decision that limits the reach of the FHA in similar lawsuits—or even, in Justice Thomas’s view, kills it softly.