The son of Mike Ditka, legendary NFL tight end, coach and NBC football analyst, was arrested for DUI in Lake County (suburban Chicago) in April 2011. At the time, some commentators questioned whether the police had a basis to approach young Ditka's vehicle in the first place.
Under the Fourth Amendment to the United States Constitution and the Illinois Constitution, you are protected from "unreasonable searches and seizures. In order to further those protections, the police must obtain a search or arrest warrant, although the courts have carved out numerous exceptions to the warrant requirement.
Therefore, not every citizen encounter with law enforcement constitutes a seizure that requires a warrant. In the realm of traffic and DUI law the most important case is Terry v. Ohio 392 US 1, 20 L.Ed. 2d 889 (1968), where the United States Supreme Court ruled that if police had a "reasonable suspicion" that someone had committed or was about to commit a crime, the police could initiate what is known as an "investigatory stop".
On the other hand, a mere "hunch" of illegal activity is insufficient to justify a Terry stop. People v. Drewes, 278 Ill. App. 3d 768, 215 Ill. Dec. 445 (3d. Dist. 1996). Whether or not a Terry stop is reasonable requires a balancing of the public's interest in safety and the individual's right to personal security and freedom. People v. Smithers, 83 Ill.2d.430,434 (1980)
In the Ditka case, the evidence showed that Ditka was sitting in a black Hummer in the parking lot of his Deerfield housing complex when the officer approached him. The officer said he asked Ditka to exit the vehicle after he smelled a strong odor of alcohol, according to a police report.
The judge determined that the officer had no reason to believe that Ditka had committed a crime when the officer approached his vehicle. The fact that after approaching the vehicle, the officer determined that Ditka had a strong odor of alcohol on his breath and that he submitted to a portable breath test (PBT) is not sufficient to overcome the Constitutional violation.
In other words, since the initial approach was illegal, the fact that the officer's vague suspicions turned out to be correct does not make a bad stop good. To hold otherwise would be to subject all of us to random searches and seizures.
Once a judge determines that a stop (or in the Ditka case, the approach) is illegal, all the evidence the police gathered after the stop is considered "fruits of the poisonous tree". In other words, the police cannot benefit from an illegal stop by still being allowed to use the information they gather following the illegal stop
This is known as the "exclusionary rule". The United States Supreme Court established this rule in the case of Mapp v. Ohio, 367 U.S. 643 (1961)
Once the judge excluded the evidence that the police gathered following the illegal stop, the prosecuting authorities had no facts upon which they could convict Ditka of DUI. They were therefore forced to drop the DUI charges against him and set him free.