FORT LAUDERDALE, Fla. — The prostitution sting that ensnared billionaire Robert Kraft was doomed from the get-go because of a string of law enforcement missteps, according to court observers who have watched the case quickly unravel.

What began as authorities’ mission to bust criminal activity in massage parlors across Florida has turned into a monumental legal victory for Kraft and others charged with soliciting prostitution.

The defendants have won rulings in their favor, including a watershed moment this past week when the judge in the Kraft case prohibited prosecutors from using secretly recorded sex videos.

“This case has been bungled from the beginning, in every way,” said Joseph Tacopina, a former New York City prosecutor who recently filed a federal class-action lawsuit claiming cops violated constitutional privacy rights by using covert cameras in a Jupiter spa.

From illegal video recordings to illegal traffic stops, here’s how it all collapsed:

PUTTING UP A FIGHT

Palm Beach County prosecutors say it was simply Kraft’s “bad luck and bad timing” that he happened to be in the Orchids of Asia Day Spa when the secret police cameras were turned on.

But another view is that it was their terrible luck that Kraft, a 77-year-old who has a home in Palm Beach, was among the people Jupiter police caught in the act.

In all previous prostitution stings at South Florida massage parlors — including a few with similar sneak-and-peek warrants for secret cameras — the cases resolved quietly and mostly out of the spotlight.

Few if any people charged ever challenged the prosecutions. They paid fines and performed community service hours, to avoid embarrassment.

This time was very different. Even before Kraft entered the picture, Americans were more sensitive to government snooping in their lives.

After the filing of criminal charges against a proven winner in the New England Patriots boss — with endless resources and legal firepower — prosecutors had a battle on their hands.

Kraft made a sheepish public apology, but also employed a national legal team with a motto of “playing to win.”

And they did just that, after picking apart practically every aspect of the police investigation and the arguments made by prosecutors.

“The whole thing was infected and illegitimate,” said Richard Kibbey, a defense attorney who represents a dozen men charged like Kraft.

Kibbey, from Martin County, raised similar challenges on behalf of his clients. He questions why law enforcement went to extreme lengths by using secret cameras to stop prostitution.

“Somebody should have realized the significance of the fact that this is such an extraordinary invasion of privacy,” Kibbey said. “It just seemed to be fast-tracked and green-lighted and once it got momentum, nobody wanted to interrupt it.”

NO SIGN OF HUMAN TRAFFICKING

In February, law enforcement agencies publicly revealed they hid recording devices during investigations of 10 spas from Jupiter to Orlando.

They said massage parlors were shut down and several women were charged with pocketing hundreds of thousands of dollars from running prostitution houses. Nearly 300 men were charged overall across Florida.

Officials said their efforts were aimed in part at targeting suspected human trafficking at the massage parlors. They pointed to state health department inspections suggesting that sex workers from Asia were living at the businesses.

“Obviously our concern in this investigation centers around … the possibility of victims of human trafficking, the appearance of that,” Jupiter Police Chief Daniel Kerr said in February, adding that customers enable such illicit businesses to “flourish.”

State Attorney Dave Aronberg called human trafficking “evil in our midst,” adding that there is “the cold reality that many prostitutes in cases like this are themselves victims, often lured into this country with promises of a better life.”

But Aronberg’s office walked back the claims, telling Kraft’s judge that there was no evidence of human trafficking. It was just misdemeanor solicitation of prostitution charges for the men, and felony charges of making money from prostitution for the women.

Officials have said they hoped the sex workers would cooperate with investigators so they could bring more serious charges. That didn’t happen.

Kraft’s lawyers ripped the authorities for misleading a judge into approving the sneak-and-peek warrant by providing a “false narrative of human trafficking.” They also accused officials of attempting “to deceive the public and justify law enforcement’s overreach” with the “clandestine video surveillance.”

‘SERIOUS FLAW’ IN THE WARRANT

After judges approved the sneak-and-peek warrants, police used “tactical ruses” to clear out the businesses so they could install the cameras in the massage rooms and the lobby. The cops said they needed to investigate a suspicious package, creating a bomb scare.

Once the cameras were rolling at Orchids of Asia, Kraft arrived at 4:44 p.m. Jan. 19 and about 11 a.m. Jan. 20, according to police. Prosecutors described the encounters in graphic detail, noting how Kraft paid in cash and then got completely naked for sex acts.

The videotaping at the business lasted for five days, leading to the charges against Kraft and 24 other men.

Prosecutors argued that Kraft lacked “a legitimate claim to an expectation of privacy and, even less so because he was present — on both occasions — to conduct criminal business transactions.” But Kraft challenged the warrant — which had permitted the use of secret cameras — as unlawful.

Palm Beach County Judge Leonard Hanser agreed that planting cameras was necessary to infiltrate crime. “The unique circumstances of a massage room creates the need for an unusually intrusive law enforcement technique,” Hanser wrote.

The judge also agreed with prosecutors that the police weren’t obligated to use other common tactics for the prostitution sweeps, such as using undercover officers.

But Hanser concluded the warrant still broke federal law, because police didn’t do enough to focus only on crimes and to minimize the cameras’ intrusiveness. At all of the spas with the secret cameras, police wound up recording people receiving lawful services, even though the focus was supposed to be only on men paying for sex acts.

Failing to be vigilant and not record women “is a serious flaw in the search warrant, especially considering that the search warrant did not allege women were seeking illegal contact,” Hanser wrote. He called it “unacceptable” that “some totally innocent women and men had their entire lawful time spent in a massage room fully recorded.”

All massage-parlor customers have a reasonable expectation of privacy under the U.S. Constitution, regardless of whether or not they went there for a lawful massage, the judge found.

After the Kraft case made headlines around the world, some of those innocent people sued Jupiter police and the state attorney over the videos. That case is pending.

Hanser also signed an order temporarily restricting prosecutors from releasing to the public the videotapes featuring Kraft, over the objection of media outlets including the South Florida Sun Sentinel. Media lawyers argue the public has a right to see evidence in a pending criminal case.

Kraft’s lawyers now want to have them permanently sealed.

TRAFFIC STOPS DEEMED ILLEGAL

Another controversial aspect of the case is how Jupiter police officers pulled over cars of people who had just left the spa.

Prosecutors explained that the cops weren’t going after actual traffic violations. It was just a legal way to obtain the identities of people who were videotaped committing crimes.

“No traffic violation need occur,” they wrote, adding the officers had no clue about Kraft’s identity until they pulled over his chauffeur-driven Bentley and looked at his Massachusetts driver’s license. Kraft also made small talk and flashed a Super Bowl ring.

But Kraft’s legal team, led by Alex Spiro, William Burck and Jack Goldberger, argued there had to be a true traffic violation to justify the stop.

They also said that because the videos were illegal, the identification of Kraft also had to be thrown out. Hanser agreed on that point.

“So these car stops they made based on the video surveillance, they’re improper, certainly not admissible,” Tacopina, the New York lawyer, said. “It’s the fruit of the poisonous tree.”

PROSECUTORS’ NEXT MOVE

Judges in Palm Beach, Martin and Indian River counties declared in rulings this month that the warrants were illegal and none of the sex video evidence can be used to prosecute Kraft or the other men caught in the bust.

That means the misdemeanor prosecutions won’t proceed unless a state appeals court overturns the trial judges’ rulings. Kraft’s prosecutors announced Friday their intention to appeal Hanser’s order; Kraft’s lawyers say they aren’t worried.

“Aronberg is acknowledging he has no case without the illegal video recordings that four Florida judges have now found to be unconstitutional,” Burck said in a statement. “No evidence means no trial.”

“So the state had only two options — drop the case or appeal,” Burck continued. “They chose to appeal, but we are confident the appellate court will agree with Judge Hanser and the other judges who threw out their illegally obtained evidence.”

So the case now heads to the 4th District Court of Appeal in West Palm Beach, and perhaps the Florida Supreme Court will have the final say one day.

Some observers say this is just a move for prosecutors to “save face” for now and delay defeat for several months or longer.

The trial judges were clear the cops crossed the line by recording men and women who were doing nothing wrong.

“As such it is incumbent upon the government that the rights of private, law-abiding citizens are not infringed upon during that surveillance,” wrote Judge Nicole P. Menz in Vero Beach, in her order Thursday.

So, all of the men accused of crimes got the benefit of having the video evidence removed from the prosecutions.

“The rule of law ultimately prevailed, which is great, but at the cost for all these people and their families,” Kibbey said. “It should have never happened in the first place.”