All things considered, it was not a bad day at the Supreme Court for Aldo, a drug-hunting German shepherd from the Florida Panhandle. But his crime-fighting colleague from Miami, a chocolate Lab named Franky, has reason for concern.

The justices spent an animated two hours Wednesday considering the reliability of drug-sniffing dogs and, separately, whether the police can bring one to your front door in hopes of sniffing out illegal activity.

Along the way, Girl Scout cookie peddlers, traveling salesmen, neighbors bearing cockapoos, bloodhounds chasing Jack the Ripper and an imagined invention called the “smell-o-matic” made an appearance.

The court is reviewing two decisions from the Florida Supreme Court. In one, it threw out a truck search that came after Aldo’s alert that drugs might be inside. The makings of methamphetamine were found, but the Florida justices said the trial judge did not know enough about Aldo’s reliability to rule that the search was proper.

The other case — and the one that drew the more heated debate — was about Franky. Miami-Dade County police, acting on a tip, brought the dog to the front door of Joelis Jardines, whom they suspected of transforming his home into a “grow house” for marijuana.

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After sniffing around Jardines’s walk and another area of the house, Franky signaled a discovery at the front door. The police used that to get a warrant to search the home, where they seized 25 pounds of marijuana and saw Jardines trying to escape out of a back window.

The Florida Supreme Court said the initial intrusion of the police and Franky onto Jardines’s front porch was a violation of the expectation of privacy a person has in his home.

Former solicitor general Gregory G. Garre, representing Florida in appealing the state high court’s decisions, reminded justices they had never ruled that dog drug sniffs were covered under the constitutional definition of a “search.” They reveal only contraband, which the Constitution does not protect, according to previous rulings.

But he quickly came under fire from justices worried about the sanctity of the home.

The objections came first from conservatives — Justices Antonin Scalia and Anthony M. Kennedy — and then from the liberal wing of the court.

Police are not allowed to go to the area around someone’s home to search for illegal activity without a warrant, Scalia said. “Why isn’t it the same thing with the dog?” he asked. “This dog was brought right up to the door of the house” in the hope of finding drugs inside.

Garre said a police officer — or anyone else — is allowed to go to someone’s door. “Going back to the common law . . . there is an implied consent for people, visitors, salesmen, Girl Scouts, trick-or-treaters, to come up to your house and knock on the door . . . ,” Garre began.

“Yes, but not implied consent for the policeman to come up with the dog,” interrupted Justice Ruth Bader Ginsburg. “The only purpose of the dog is to detect contraband.”

Justice Elena Kagan noted the court has held that police cannot use heat-detection devices outside a home to indicate the presence of lamps used in growing marijuana inside.

Why, she asked, is a dog’s enhanced sense of smell different from a machine, say a “smell-o-matic,” given the court’s previous decision?

Garre noted that dogs have been used for centuries, including tracking Jack the Ripper.

Kagan said that meant Garre’s distinction was that “we should not understand Franky as kind of a sense-enhancing law enforcement technology, but we should think of him as just like a guy.”

Jardines’s attorney, Miami public defender Howard K. Blumberg, had trouble with Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr.

Alito attacked Blumberg’s assertion that the act of a police officer bringing a dog to someone’s front door was a “trespass” under the Fourth Amendment. The justice asked whether Blumberg could name “any trespass case in the last 500 years in any English-speaking country” with that holding.

If many of the justices had concerns about privacy, though, they did not appear ready to impose new requirements for proving that the dogs are reliable.

In Aldo’s case, the Florida Supreme Court said the state must produce records of certification and training and reports of accuracy in the field when a dog’s alert is challenged.

Garre said the Florida court calls for “what we think is an extraordinary set of evidentiary requirements that, in effect, puts the dog on trial” when the defendant wants to supress the evidence gathered.

Garre told the court that it would be fine for the defendant to question the dog’s handler about his performance, but the Florida court produced a long list of evidence that must be maintained on every dog.

When the attorney for Clayton Harris, the man arrested after Aldo’s alert, told the justices that canines should not be exempt from examination, several justices told him they were not.

“I didn’t think they disagreed” about what a state judge may do, Justice Stephen G. Breyer told the lawyer, Glen P. Gifford. “I thought they disagreed about what he must do.”

The cases are Florida v. Harris and Florida v. Jardines .