OPINION
MERRITT, Circuit Judge.In this drug case, the District Court suppressed evidence of a methamphet*565amine laboratory seized by police officers as a result of a warrantless search of a trailer home and garage on a remote country road in a farming area of West Tennessee. The officers did not seek judicial review and approval in advance as the Fourth Amendment requires except in extraordinary circumstances. The government appeals the suppression order primarily on the ground that the possible destruction of evidence justified the war-rantless search under the “exigent circumstances” exception to the warrant requirement. Secondarily, the government also claims as an alternative theory that the officers obtained a valid consent to search after their forced entry at the home. We will first set out the principles governing warrantless searches for evidence and then apply those principles to the situation before us. We will affirm the judgment of the District Court because here there was no emergency justifying a warrantless search and the officers anticipated that they would conduct the search and could easily have obtained a search warrant.
I. Principles Limiting Warrantless Searches Based on “Exigent Circumstances”
The principles governing warrantless searches based on “exigent circumstances” are fairly well settled. In the Fourth Amendment, the Founders required a warrant for searches and seizures because they did not trust constables, sheriffs and other officers to decide for themselves when they had probable cause to search houses, individuals and places of business. The first and most important principle is that searches must ordinarily be cleared in advance as a part of the judicial process. In Coolidge v. New Hampshire, 403 U.S. 443, 454-55, 91 S.Ct. 2022, 29 L.Ed.2d 564 (1971) (footnotes omitted), the Supreme Court explained:
Thus the most basic constitutional rule in this area is that “searches conducted outside the judicial process, without prior approval by judge or magistrate, are per se unreasonable under the Fourth Amendment — subject only to a few specifically established and well-delineated exceptions.” The exceptions are “jealously and carefully drawn,” and there must be “a showing by those who seek exemption ... that the exigencies of the situation made that course imperative.” “[T]he burden is on those seeking the exemption to show the need for it.”
(Emphasis added and footnotes omitted.) In order for a warrantless search to pass muster, probable cause must exist, but “no amount of probable cause can justify a warrantless seizure,” id. at 471, 91 S.Ct. 2022, because, in addition, the cause of the search must be based on an “emergency” and hence, “inadvertent” or unanticipated. “Where the discovery is anticipated, where the police know in advance the location of the evidence and intend to seize it, the situation is altogether different.” Id. at 470, 91 S.Ct. 2022.
Under these principles, officers must seek a warrant based on probable cause when they believe in advance they will find contraband or evidence of a crime. They must articulate the basis of their belief in the affidavit and bring the matter before a magistrate. When the police go to a home with the intention of searching for evidence, they may not forgo a warrant.
When there is neither a warrant nor consent, courts will only permit a search or seizure to stand under extraordinary circumstances. In McDonald v. United States, 335 U.S. 451, 69 S.Ct. 191, 93 L.Ed. 153 (1948), “three police officers [without a warrant] surrounded the house” they had had under surveillance for two months where they believed that McDonald was conducting a numbers racketeering operation. “While outside the *566house, one of the officers thought he heard an adding machine. These machines are frequently used in the numbers operation. Believing that the numbers game was in process, the officers sought admission to the house.” Id. at 452, 69 S.Ct. 191. They entered the home and seized the evidence while the numbers operation was in progress. The Court suppressed the evidence:
Where, as here, officers are not responding to an emergency, there must be compelling reasons to justify the absence of a search warrant .... We will not assume that where a defendant has been under surveillance for months, no search warrant could have been obtained .... No reason, except inconvenience of the officers and delay in preparing papers and getting before a magistrate, appears for the failure to seek a search warrant .... Absent some grave emergency, the Fourth Amendment has interposed a magistrate between the citizen and the police.
Id. at 454-55, 69 S.Ct. 191 (emphasis added). The “imperative” and “anticipated” language of Coolidge and the “grave emergency” language of McDonald are designed to insure that officers will seek a warrant based on probable cause when they have a belief in advance that they will find contraband or evidence of a crime. They may only forego a warrant in the case of a true exigency or emergency.
Moreover, for a warrantless search to stand, law enforcement officers must be responding to an unanticipated exigency rather than simply creating the exigency for themselves. In United States v. Richard, 994 F.2d 244 (5th Cir.1993), the officers were conducting surveillance of a hotel room occupied by suspects. The officers approached the door, knocked, and announced that they were police officers. The officers heard the sound of people talking softly, heard doors or drawers slamming, and footsteps moving about. The officer kicked the door open and entered the room without a warrant. Although officers claimed that they did not have probable cause to obtain a warrant in the beginning, the evidence suggested otherwise. Id. at 248. The court held that the officers could have secured the area around the room while they waited for a warrant; but because they did not, the officers had created the exigent circumstances that they wanted to rely on to justify their warrantless entry. A “war-rantless entry became a foregone conclusion once officers knocked.” Id. at 249-50. McDonald and Richard stand firmly for the proposition that warrantless searches are not permitted when the only exigency is one that is of the officer’s creation.
Likewise, in Ewolski v. City of Brunswick, 287 F.3d 492, 504 (6th Cir.2002), we reviewed a number of the “ereated-exigen-cy” cases that apply the emergency and inadvertence principle which, we said, cannot be met “if the police controlled the timing of the encounter giving rise to the search.” Our review concluded that “the created-exigency cases have typically required some showing of deliberate conduct on the part of the police evincing an effort intentionally to evade the warrant requirement.” Id: (Emphasis added.)
II. Application of “Exigent Circumstances” Principles to the Facts of this Case
The warrantless search in this case turned up extensive evidence of the operation of an elaborate meth laboratory that the police believed was at the premises when they arrived. At the suppression hearing below, the government offered evidence from the lead officer of the search, George Freeman, a narcotics officer for the Sheriff of Fayette County, Tennessee. He testified that four months before the search a known confidential informant advised police that the Chambers lab was *567manufacturing methamphetamine at the trailer home and garage where the search was later conducted. The informant’s identity was known and his information was clear. There is no claim that the informant was anonymous, unreliable or had not given the officers a sound factual basis for his statements. Based on the strength of the information from the confidential informant, officers conducted both an extensive surveillance of the trailer home and garage from a nearby field for three nights and later used helicopter flyovers. The surveillance uncovered frequent nighttime visits to this remote location by numerous people in cars, some with out-of-county license plates — visits that Officer Freeman believed were consistent with customers purchasing drugs from the meth lab that the informant had described.1 In addition, at the trailer home in this remote farming area, the officers observed that Chambers was using surveillance cameras and several high intensity spotlights to keep watch over the area — all of which fully corroborated the confidential informant’s report to the police. There was now strong, indeed overwhelming, evidence of multiple drug sales at the premises on a daily basis, evidence supporting the informant’s statements that a meth lab was in frequent operation at the Chambers home. But the officers took no action at this time to secure a search warrant despite the incriminating evidence in their possession. No magistrate was asked nor has any magistrate ever turned down a request for a warrant in this case.
At the suppression hearing, narcotics Officer Freeman also testified that the sheriffs office then received an “anonymous” call on October 9, 2002, three months after the surveillance. Freeman said that the caller “was adamant that I write this down and stated that the Chambers were cooking meth right there on Linwood road right now and that we had better get out there, and hung up the phone.” The police now had evidence from a known confidential informant, the strong corroboration obtained as a result of their extensive surveillance and evidence from an anonymous caller that the drug was being manufactured at the Chambers lab that day. Still the officers did not seek a warrant.
Instead, the officers performed a war-rantless “knock and talk investigative technique” that Officer Freeman had been taught, a method of investigation requiring the officer to go to a home and knock on the door and ask questions in an effort to gain consent to search.2 While en route to *568the Chambers’ home, Freeman called Officer Feathers of the federal DEA task force to advise him to be ready for a search at the Chambers residence. Three cars with armed deputies drove to the house to participate in this so-called “consensual” encounter.
They knocked on a glass entry door of the trailer home. A woman came to the glass door to answer the knock. She retreated when she saw that the police were at the door. She called out that there were police at the door; and the police heard, according to Officer Freeman, footsteps scurrying inside the trailer as the woman went into another room. Freeman then used the knock and the occupant’s refusal to talk as the justification for entry. The police officers immediately went through the door with guns drawn and into the trailer home to begin their search. The officers had now entered the home without a warrant after appearing in three cars and after informing the DEA task force of the impending search. Why and how exactly the officers thought that the occupants were going to destroy an entire operating meth laboratory with heavy equipment and drums of chemicals in two detached buildings is not explained.
After searching for a few minutes and finding incriminating evidence, indicating an operating meth lab, Officer Freeman read Chambers, the owner, and his wife, their Miranda rights; and the Chambers then signed a consent to search form at the request of officer Freeman. Freeman testified that Chambers was under arrest and not free to leave.
After the entry and search, Freeman called Feathers back and asked him to come. Feathers came to the premises with other officers and told Freeman that with the “information that they ... had prior on Mr. Chambers, they [the Feathers group of officers] just wanted to go ahead and stop ... and get a search warrant.” Freeman had not suggested a warrant. Unlike the sheriffs officers, these DEA officers believed a warrant necessary based on the “prior information” they had about the Chambers. They would not participate in a search based on exigent circumstances. So at that point the various officers on the premises waited for the search warrant to arrive, long after the initial search had actually been conducted after the warrantless entry.
The government’s claim that the officers did not have sufficient evidence of probable cause even to seek a warrant is more farfetched than the similar claim that the Supreme Court rejected in McDonald. Like the Court in McDonald, “[w]e will not assume that where a defendant has been under surveillance for months, no search warrant could have been obtained.” 335 U.S. at 454-55, 69 S.Ct. 191. The officers had the information from the confidential informant, the corroboration gained by them extensive surveillance and the anonymous caller evidence. They had advised the DEA in advance of the impending search. Clearly, they should have sought a search warrant. Moreover, they completely “controlled the timing of the encounter giving rise to the search.” The fact that the woman at the door called out “police” and retreated back to another room does not create an exigent circumstance. It is her constitutional right. Such a retreat and refusal to allow soldiers or armed officers into the home is every citizen’s right under the Fourth Amendment, the very reason for its creation. The exercise of this fundamental right against armed invasion of the home is certainly not, as the government seems to imply, the “equivalent” to yelling “destroy the drugs” — or “get your guns ready” or *569“try to hide or destroy the boiler and all the lab equipment.” The exercise of a constitutional right at the front door of your home not to consent to talk or allow a search does not create an exigency justifying a warrantless entry.
“The burden is on those seeking the exemption [from the warrant requirement] to show the need for it,” Coolidge, 403 U.S. at 455, 91 S.Ct. 2022. There is no showing here at all that a magistrate would not have issued the warrant earlier in the day or at some previous time, as he did later in the day upon the affidavit of the DEA Task Force. There was no exigency. We therefore conclude that the District Court did not err in its conclusion that the government has failed to show the need for an exemption from the warrant requirement of the Fourth Amendment.
The failure to seek a warrant in the face of plentiful probable cause, the timing and Freeman’s call to Officer Feathers advising him of the impending search, as well as the arrival with three cars and the immediate entry with guns drawn, taken together, meet the requirement of “some showing of deliberate conduct on the part of the police evincing an effort to evade the warrant requirement.” Even were the Court to find exigent circumstances, the record indicates that any exigency was calculated by the police in order to facilitate their warrantless search.
The freedom from armed intrusions of the home “outside the judicial process, without prior approval by judge or magistrate,” as the Supreme Court explained in the Coolidge case quoted above, is one of our most “basic” civil liberties. Like the rights of free speech and assembly, trial by jury and the right to counsel, it is among the civil liberties the founding generation fought for and included in our founding documents — a liberty that the American people have pointed to with pride for 200 years. We should continue to take seriously the rule that judicial review is necessary to allow such intrusions and not water down the warrant requirement because advanced judicial clearance is an inconvenient or inefficient practice that the police or the military are too busy, or otherwise unwilling, to observe.
III. The Consent to Search Issue
Within a few minutes after the warrantless entry, Officer Freeman encountered Chambers, effectively advised him that the officers had looked around briefly and found evidence of methamphetamine use and manufacture, read him his Miranda rights and asked him to sign a consent to search further. Officer Freeman answered, “Yes” to the question on cross-examination, “[Chambers] was actually detained, is that correct, he is not free to leave at the time he was asked for the consent to search?” At that point, after the illegal entry and after the officers had found some evidence of the methamphetamine lab they had expected to find, and after Chambers was not free to leave, Chambers and his wife then signed a consent to search form.
The government’s brief correctly states the standard for consent to search after an illegal entry:
When an individual consents to a search after an illegal entry is made, the consent is not valid and “suppression is required of any items seized during the search..., unless the taint of the initial entry has been dissipated before the ‘consents’ to search were given.” Buchanan, 904 F.2d at 356 (quoting United States v. Vasquez, 638 F.2d 507, 527 (2d Cir.1980), cert. denied, 450 U.S. 970, 101 S.Ct. 1490, 67 L.Ed.2d 620 (1981)). “Dissipation of the taint resulting from an illegal entry,” this Court has held, “ordinarily involves showing that there was some significant intervening time, *570space, or event.” Id. (quoting Vasquez, 638 F.2d at 528). Finally, it is the government’s burden to show that the defendant’s consent “was sufficiently an act of free will to purge the primary taint of the unlawful invasion.” Buchanan, 904 F.2d at 356 (emphasis in original).
We agree with the District Court that the consent to search forms were executed by Chambers and his wife only a few minutes after the illegal entry by three police officers, after they had conducted a brief preliminary search and found evidence of a methamphetamine lab and after Chambers was no longer free to leave and therefore effectively under arrest. We agree with the District Court as well that these events created a highly coercive atmosphere and that “it would be reasonable for Chambers to think that refusing consent would be a futile gesture amounting to no more than ‘closing the barn door after the horse is out.’ ” The District Court credited Chambers’ testimony: “He asked me if I had the keys to the shed [where the anhydrous was stored], and he had me under arrest, I didn’t know what else to do ... I had no choice in it.” (Op., p. 23, App. 107.) Based upon the evidence in the case, we find no error in these findings and the conclusion of the District Court as follows:
Considering the totality of the circumstances, the Court finds that Chambers’ consent was the product of the prior illegal entry into his residence. Accordingly, it is submitted that the government has not carried its burden to show by a preponderance of the evidence through clear and positive testimony that Chambers’ consent was voluntary.
(Op. p. 24, App. p. 108.)
Accordingly, the judgment of the District Court is AFFIRMED.
. Officer Freeman testified as follows:
Q: Now I started this line of questioning by asking you if anything unusual happened, why was this activity significant to you?
A: .... So with the vehicles coming up and down the road and stopping there for, you know, ten, 15, 20 minutes and then leaving, it seemed to be significant as far as in and out quick, frequent, which is consistent with narcotics activity-
Q: Why did you reach that conclusion?
A: It’s been my experience during narcotic investigations that a house where people pull up, either one or more occupants stay in the vehicle where the engine is left running and they go in the house for a short period of time and then leave, through- — through my observations as a police officer that is consistent with narcotics sales.
Testimony of George Freeman, Suppression Hearing, Feb. 26, 2003, at pp. 23-24 (J.A. at 166-67).
. "Courts have defined [knock and talk] as 'a noncustodial procedure [in which] the officer identifies himself and asks to talk to the home occupant and then eventually requests permission to search the residence.’ ” United States v. Hardeman, 36 F.Supp.2d 770, 777 (E.D.Mich.1999) (citation omitted). Courts generally have upheld this investigative proce*568dure as a legitimate effort to obtain a suspect’s consent to search.