Early Tuesday morning, Chief Justice John Roberts Jr. made a rare appearance in the U.S. Supreme Court’s ground-floor press room, welcoming back reporters after the court’s long winter recess.

Without revealing which ones they were, Roberts told the press corps that the court would soon be issuing several opinions, adding that if anyone had scheduled a lunch, “you might want to push it back.”

An hour later, Roberts was proven right, as the court handed down four opinions on issues ranging from antitrust to drug-sniffing dogs, also adding a major campaign finance case to its docket for next term. The top developments of a busy Tuesday:

Campaign finance: The court agreed to hear McCutcheon v. Federal Election Commission, a challenge to one of the pillars of the 1976 Buckley v. Valeo decision, which has governed campaign regulation ever since. The Buckley ruling permitted government regulation of individual contributions to candidates, while giving candidates freer rein under the First Amendment to spend campaign money. The McCutcheon case targets contribution limits.

Challengers, including the Republican National Committee, say the aggregate limits on individual contributions to candidates violate their First Amendment rights. The most recent biennial limits were $46,200 to candidates and no more than $70,800 to party committees and political action committees. “If the current aggregate limits were to be struck down, one-, two- and even three-million dollars in contributions could easily be funneled by a single donor to his or her party and candidates of choice,” said Tara Malloy of the Campaign Legal Center, which has filed a brief in the case. “Corruption, or at the very least the appearance of corruption, would be the rule rather than the exception in Washington.”

Antitrust: The Federal Trade Commission won a significant round in an antitrust suit filed against a Georgia-created hospital authority that had tried to invoke the immunity that states enjoy when they engage in anti-competitive actions. In the court’s unanimous ruling in FTC v. Phoebe Putney Health System Inc., Justice Sonia Sotomayor said that states are immune only when a local government acts pursuant to a “clearly articulated and affirmatively expressed state policy to displace competition.”

The Georgia law that empowered localities to create hospital authorities and provide health care services did not have this kind of explicit statement, Sotomayor said, so the FTC action could continue against the consolidation and “near monopoly” of health care services created by the hospital authority in Albany/Dougherty County.

The ruling may be a mixed blessing for the health care industry, said Jay Levine of Bradley Arant Boult Cummings’ Washington office, an expert on antitrust issues that hospitals face. “This might be welcome news to some hospitals who feel that their local authority has been gaining too much power via acquisitions of competing hospitals. At the same time, it certainly takes away a means by which a hospital transaction can escape the scrutiny of antitrust regulators.”

Steve Cernak of Schiff Hardin’s Ann Arbor, Mich., office said of the ruling: “The result will be that parties, like the hospital authorities—or state licensure boards or others acting under state delegation—will need to point to something a little more explicit from the state legislature to get the benefits of immunity from the antitrust laws.”

Police searches: A unanimous court joined in striking down a Florida Supreme Court ruling that had undermined the utility of police searches using drug-sniffing dogs. In the decision, Florida v. Harris, Justice Elena Kagan wrote that the Florida ruling imposed an “inflexible checklist” for determining the reliability of drug-detection dogs that made it difficult for police to meet the “probable cause” test for arresting someone based on a canine search. Kagan substituted instead a “common-sense” test for reliability, adding that “[a] sniff is up to snuff when it meets that test.”

The case involved Aldo the dog, who alerted police to the presence of drugs during a search of a truck stopped in a routine traffic stop. A related case, Florida v. Jardines, involving a search by a dog named Franky outside a house, was argued the same day as the Harris case last October, but a ruling was not released Tuesday—suggesting the possibility of a different outcome under the facts of that case.

In a separate case, Bailey v. U.S., the court ruled against police, finding that a search warrant of a house does not allow police to search people who left the premises and were detained seven-tenths of a mile away. Justice Anthony Kennedy wrote for a 6-3 majority that the distant search poses “an additional level of intrusiveness” and creates the “additional indignity of a compelled transfer back to the premises, giving all the appearances of an arrest.” Breyer dissented, joined by justices Clarence Thomas and Samuel Alito Jr.

International custody disputes: The justices agreed unanimously that U.S. courts still have a role to play in overseas custody disputes, even if the child is abroad and chances are slim for him or her to be returned to the United States. Roberts announced the ruling in Chafin v. Chafin, involving efforts by Jeffrey Chafin to force the return of his daughter, currently in Scotland with his ex-wife, Lynne Chafin, a Scottish citizen.

Acting under the Hague Convention on international child abduction, the mother obtained a federal district court order returning their daughter to her in Scotland. The father fought for custody of the child, but the U.S. Court of Appeals for the Eleventh Circuit dismissed the appeal as moot because U.S. courts were powerless to grant relief. The high court reversed, finding that the possibility of the child being returned to the United States is not so remote that the case is rendered moot.

“Enforcement of the order [to return the child] may be uncertain if Ms. Chafin chooses to defy it, but such uncertainty does not typically render cases moot,” Roberts wrote. The chief justice also made a special point of urging U.S. courts to expedite the handling of international custody disputes “for the sake of the children who find themselves in such an unfortunate situation.”

Tony Mauro can be contacted at tmauro@alm.com.