It depends on many things, but you may very well have a case. In a recent Indiana case at
http://fourthamendment.com/blog/index.php?blog=1&s=drinking&sentence=AND in a civil suit regarding something like this (Although the discussion involves the issue of qualified immunity, it's relevant because the decision points to the fact that a reasonable officer should have known such a search was illegal.):
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No qualified immunity to officer who entered a house without a warrant to break up an underage drinking party
I can't summarize this better than the judge did, and the court provides a good analysis of application of qualified immunity: Pribble v. Town of Winona Lake, 2007 U.S. Dist. LEXIS 28517 (N.D. Ind. April 17, 2007):
According to Plaintiff Charles J. Pribble, Jr., in the early morning hours of May 15, 2005, Officer Paul Heaton was driving around a neighborhood of Winona Lake looking for an underage drinking party that was rumored to be occurring. When he saw a bunch of cars parked outside the Pribble home and saw through a large window that young people were drinking inside, he believed he had found what he was looking for. He knocked on the door to investigate, but when the wily person who answered the door asked if Heaton had a warrant, he replied that he didn't need one. Heaton then forcibly entered the house and arrested everyone inside, including Pribble. This left Pribble's father unhappy and prompted him to file a lawsuit in state court against Officer Heaton, the town of Winona Lake, and an unknown private security officer who allegedly accompanied Heaton during the raid. Defendants then removed the case to this Court. Pribble alleges violations of his Fourth, Fifth, and Sixth Amendment rights and a common law claim of false arrest and imprisonment.
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Defendants maintain that Plaintiff's claim of unreasonable search and seizure under the Fourth Amendment should be dismissed because Officer Heaton had probable cause to enter the home and make the arrest. The question of probable cause is typically "a proper issue for a jury if there is room for a difference of opinion concerning the facts or the reasonable inferences to be drawn from them." Maxwell v. City of Indianapolis, 998 F.2d 431, 434 (7th Cir. 1993). Defendants' own cases (most of which are Indiana state court cases, which do not control our interpretation of the federal Constitution) reflect this principle. See Earles v. Perkins, 788 N.E.2d 1260, 1264 (Ind. App. 2003) (reviewing grant of summary judgment; "The determination of probable cause is a mixed question of law and fact."); Miller v. City of Anderson, 77 N.E.2d 1100 (Ind. App. 2002) (affirming summary judgment; plaintiff's case must fail "if the record as a whole reflects probable cause for the arrest" (emphasis added)). Plaintiff's complaint alleges that "Heaton advises he allegedly observed an underage drinking party occurring by looking into the house from the road" (Compl. P 8 (emphasis added)), but the Court does not interpret that allegation to mean that Plaintiff admits Heaton's version of events or concedes that Heaton had probable cause.
More importantly, Defendants incorrectly assert that Heaton only needed probable cause in order to justify his entry into a private residence. That is plainly not the standard. In the absence of a warrant, a police officer needs both probable cause and the presence of exigent circumstances, such as a risk of physical harm or the imminent destruction of evidence, that make it reasonable for the officer to enter even though he does not have a warrant. United States v. Karo, 468 U.S. 705, 715 (1984) ("Searches and seizures inside a home without are presumptively unreasonable absent exigent circumstances."); Payton v. New York, 445 U.S. 573, 576, 590 (1980) (absent exigent circumstances, police officers may not enter an individual's home without consent in order to make a warrantless arrest for a felony, even if they have probable cause); Mincey v. Arizona, 437 U.S. 385, 393-94 (1978) ("[W]arrants are generally required to search a person's home or his person unless 'the exigencies of the situation' make the needs of law enforcement so compelling that the warrantless search is objectively reasonable under the Fourth Amendment.").
Taking the complaint on its face, Officer Heaton entered the house without a warrant because he saw some young people drinking inside, not because he perceived any particular danger or risk inside. Cf. Brigham City v. Stuart, 126 S.Ct. 1943, 1944 (2006) (exigent circumstances were present where officers, who had responded to a 3:00 a.m. call about loud party, heard an altercation as they approached the house, saw juveniles drinking in backyard, and upon looking through screen door and windows, saw an altercation in which a juvenile punched an adult, causing him to spit blood). Once inside, he began arresting people, including Plaintiff. The complaint does not indicate what Heaton saw when he entered the home, so it is unclear whether Heaton had probable cause to arrest Plaintiff once he was inside the house. The existence of both probable cause and exigent circumstances are issues that require the development of facts. See Jacobs v. City of Chicago, 215 F.3d 758, 770 (7th Cir. 2000) (dismissal was inappropriate where allegations in complaint gave no indication that exigent circumstances existed for warrantless search). For now, it is enough that Plaintiff has plainly stated a claim for relief under the Fourth Amendment.
Defendants insist, however, that Officer Heaton is entitled to qualified immunity for his actions. State officials occupying positions with discretionary authority and who are acting under color of state law may be immune from claims that he violated a plaintiff's constitutional rights. Siegert v. Gilley, 500 U.S. 226, 231 (1991). But the pleading stage of a case is not the appropriate time to raise qualified immunity. As the Seventh Circuit has noted, "a complaint is usually not dismissed under Rule 12(b)(6) on qualified immunity grounds." Alvarado v. Litscher, 267 F.3d 648, 651 (7th Cir. 2001). This is because qualified immunity is a defense. "Because an immunity defense usually depends on the facts of the case, dismissal at the pleading stage is inappropriate: '[T]he plaintiff is not required initially to plead factual allegations that anticipate and overcome a defense of qualified immunity.'" Id. at 651-52, quoting Jacobs, 215 F.3d at 765 n.3.
To evaluate a defense of qualified immunity, the Court must first determine whether Plaintiff has stated a violation of his constitutional rights, and then determine whether those rights were clearly established at the time that the violation allegedly occurred. Jacobs, 215 F.3d at 766. The first step has been satisfied; as discussed above, we have already determined that Plaintiff has stated a claim for violation of his Fourth Amendment rights. In order to satisfy the second step, the plaintiff must show that, in light of pre-existing law, a reasonable defendant would have known that his conduct was unlawful. Anderson v. Creighton, 433 U.S. 635, 60 (1987). It has been clearly established since the Supreme Court decided Coolidge v. New Hampshire in 1971 or Payton v. New York in 1980, that "a search and seizure carried out on a suspect's premises without a warrant is per se unreasonable, unless the police can show that it falls within one of a carefully defined set of exceptions based on the presence of 'exigent circumstances.'" Coolidge, 403 U.S. 443, 474-75 (1971). Because we don't know at this point what the circumstances were on the night in question, dismissal on qualified immunity grounds is plainly inappropriate.