Moreover, the risks posed by felons with known propensities (or stated intentions) to respond violently to law enforcement apprehension efforts are usually subject to judicially approved no-knock arrest warrants; therefore, they can be excepted from this particular element of analysis.
However, a subject who is forewarned of officers' intention to breach his home's entrance by the amount of time required by knock and announce standards presents the worst case scenario for all involved: he may be insufficiently startled to preclude any response on his part in the manner of a subject who is completely surprised (or fast asleep) at the moment of entry; but he may have just enough time to reach reflexively for stowed or secreted weapon while at the same time being deprived of sufficient reaction time and/or cognitive awareness to perceive the inadvisability of doing so under the circumstances, with deadly results. Stated very simply, a startled or groggy armed felon presents more of a danger to police, to himself, and to anyone else present at the time of a search warrant executed on his home than both a completely startled (or sleeping) subject and a completely alert subject.
Likewise, in the case of accidental execution of a valid warrant on the wrong premises, (or on the right premises where only innocent parties are present at the time of execution), complete surprise reduces the risk to all involved as compared to entry pursuant to knock and announce procedures. Especially in dangerous neighborhoods, home intrusions are not that uncommon, and experience suggests that criminal home invasion by police impersonators are a known modus operandi. Under these circumstances, even non-criminally inclined subjects may react by reaching for legally possessed defensive firearms, especially when not fully awake or aware of what is happening.
Under such scenarios, it is precisely the innocent citizen completely unaware of criminal activities of the subject of the warrant who may be least hesitant to respond with what he perceives as justified deadly force to an apparent home invasion. Ironically, the innocent person who is present in the home may, therefore, present the greatest danger to everyone involved when police breach the entrance after providing momentary notice instead of none at all.
Alternative Remedies Consistent with the Concept of Harmless Error:
Law enforcement always represents a balance of benefits and detriments to individuals and to society as a whole. Where police are free to initiate warrant-less searches based on whims or purely subjective beliefs or suspicions, society suffers from governmental oppression. Conversely, where individual rights are so absolute as to make effective law enforcement virtually impossible, society and all individuals who choose to live within it lawfully suffer, while criminals enjoy the comparative freedom to prey on those incapable of protecting themselves.
In this regard, it is also helpful to consider the implications of policy on the conduct of police procedures and the underlying motivations for police conduct that may violate constitutional guidelines. Specifically, the potential motivation for police to purposely violate constitutional requirements for securing warrants to search and arrest, or to elicit evidence of ongoing or planned criminal activity or confessions of past criminal conduct are easily understandable: violations of this nature provide access to information to which police would not otherwise be privy.
Precisely because this potential motivation correlates so directly to oppressive police conduct that violates fundamental concepts of the U.S. Constitution, exclusion of evidence obtained in violation thereof is the appropriate remedy. The alternative of allowing the wrongfully-obtained evidence at trial would provide continued motivation for similar violations to the detriment of all in society.
In comparison, the only plausible motivation on the part of police authorities to consider violating knock and announce requirements is to protect themselves from deadly resistance that is, in and of itself, prima facie unlawful. Irrespective of whether or not police comply with the knock and announce component of otherwise validly secured and executed search warrants, the evidence to which they are already entitled to search for and possess is the same.
As a general principle required if police are to be allowed to enforce laws, any remedies or compensation for improper police conduct must be provided by mechanisms that do not unnecessarily impede police procedures at the time of police action initiated in good faith. That is precisely why arrests and/or instances of imprisonment that are determined, in retrospect, to have been unlawful are addressed under civil statutes and by agency sanctions against the offending police personnel.
Resistance to arrest, even where it is unlawful, is not permitted at the time of arrests, simply because the subjective beliefs of criminal suspects cannot justify noncompliance with commands issued by police in the field. Likewise, exclusion of valid evidence by virtue of minor, superficial violations of the knock and announce requirement, (especially, when justified by exigent circumstances or officer safety), are more appropriately addressed by monetary compensation or by agency administrative sanctions than by excluding evidence to the detriment of society.
Perhaps the only exception to that notion is that police compliance with knock and announce requirements may sometimes provide those inclined to destroy inculpating evidence a momentary opportunity to do so. However, this is hardly the intent or the principle underlying the knock and announce requirement: a person maintains a constitutional right to be secure in his home and his effects; there is absolutely no constitutional right to the opportunity to destroy evidence or contraband, which is, itself, distinct felonious criminal violation.
The American criminal justice system has, by design, as well as by its evolution, developed constitutional principles intended to protect the rights of the individual from overzealous police conduct, while at the same time permitting enforcement efforts that are reasonable under the circumstances of their exercise. In keeping with the general principle that it is preferable for many guilty individuals to escape punishment than for a single innocent individual to be punished wrongfully, evidence of actual guilt must often be stricken from trial to protect the rights of everyone to be free from wrongful police conduct.
Nevertheless and despite the validity of that principle, the issue of failure to comply with knock and announce requirements must be distinguished conceptually from the failure to secure a warrant, failure to comply with the limitations in scope of a warrant, or the failure to comply with constitutional requirements of avoiding coerced admissions of guilt or evidence of other crimes. Whereas those violations all result in the elicitation of information or evidence to which police officers were not legally entitled to obtain, the knock and announce violation does not.9
Evidence secured through unlawful warrant-less searches and evidence elicited through unconstitutional coercive tactics are appropriately excluded from trial, precisely because they fail the "but for" test. Specifically, but for the constitutionally violative police tactics, the evidence would not likely have come into possession of police.
Significantly, even where police do obtain crucial inculpating evidence through unconstitutional means, the evidence may still be allowed where it is determined that even without those violations, it would have been discovered anyway.10 the essential relevance of the inevitable discovery rule first articulated by the Supreme Court in the 1984 Nix case, is that it allows for prosecutorial use of certain evidence even where, at the time of the violation, police knowingly and purposely violated constitutional requirements to secure it.
By contrast, the knock and announce violation does not produce a scintilla of evidence to which police are not already entitled by virtue of the valid search warrant.
To whatever extent constitutional violations actually produce evidence that would not have been available to police through legal means, exclusion may be the appropriate remedy. However, where the constitutional violation relates to other matters entirely, and where it does not result in a windfall of ill-gotten gains to law enforcement, excluding it from trial is wholly inappropriate and against the interests of society.
Finally, with regard to appropriate remedies for impermissible police conduct in the form of knock and announce requirement violations, the Supreme Court suggested in Hudson that when rights are violated by police in good faith execution of otherwise valid search warrants, sufficient civil remedies exist for individuals harmed by such violations without requiring the exclusion of evidence as a remedy.11 the rationale of applying remedies for technical violations of constitutionally required police procedures is to deter impermissible police conduct in pursuit of evidence of criminal conduct. The exclusionary rule is appropriately applied where police conduct violates the safeguards against seizing evidence without a warrant. It is not appropriately applied for technical violations of knock and announce procedures of otherwise valid warrant executions.