united-states admissibility
At an unlawful traffic stop, police searches the car and find the weapon used in a recent murder
<p>Say that a murder was committed. Some time after, without any justifiable reason (perhaps on a hunch, or just by coincidence), a police officer stops a car, unlawfully searches it and stumbles upon the weapon used in the recent murder.</p>
<p>What would happen in this case? Is the murder weapon inadmissible? If so, what would happen to the driver, who was most likely the murderer? Can the police arrest him, and investigate him with the hope of finding other evidence that would be enough to sentence him for the murder, despite the inadmissibility of the actual weapon? Or is the murderer in practice immune from being charged for this case, since the weapon cannot be tied to him?</p>
<p>If the weapon is considered inadmissible, is it returned to the suspect? If yes, would it also be returned even if it is of a type that the suspect is not legally allowed to own?</p>
<p>Is the weapon permanently inadmissible for all future, or could it be used in a later court proceeding?</p>

<p>So, lets say for argument's sake the search is illegal (we'll discuss scenario later).</p>
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<p>Is the murder weapon inadmissible?</p>
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<p>No.  Evidence seized in an illegal search is inadmissible for use in court, as to allow it would reward the state for breaking the law.  At time of arrest it's still evidence and depending on what other evidence comes out might not be inadmissible (More on this later).  If the knife is the only thing linking the driver to the murder, then it's inadmissible.</p>
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<p>What would happen to the driver, who was most likely the murderer?</p>
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<p>At this stage, the driver might be arrested and charged... inadmissibility is a matter for pre-trial motions, which takes place after the cop made the search.  Whether the guy is a murder or not, he is a suspect who has been accused.</p>
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<p>Can the police arrest him, and investigate him with the hope of finding other evidence that would be enough to sentence him for the murder, despite the inadmissibility of the actual weapon?</p>
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<p>This all takes place before the inadmissibility of evidence is declared, so they certainly could investigate the guy, cuff him, read him his rights, book him, Danno, and put him in jail to help build their case.  HOWEVER, if the knife is the only thing linking the man to the crime, then all of this becomes what's called &quot;Fruit of the Poisonous Tree&quot;.  Because the knife was used as the sole evidence to secure search warrants against the suspect, and should the knife become inadmissible, anything that resulted from the execution of the warrants is itself inadmissible.</p>
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<p>is the murderer in practice immune from being charged for this case, since the weapon cannot be tied to him?</p>
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<p>Not entirely.  Rarely is a murder weapon needed to secure a conviction.  Not only that, but while the search is illegal, there is an exception called &quot;Inevitable Discovery&quot; which holds that evidence seized illegally initially may still be admissible if the cops can show that the legally obtained evidence would have led to the knife.  Suppose they had CCTV footage and captured the man entering the area of the scene and found out he had a connection to the victim, and got a warrant that would have included his car... that would mean the knife is admissible even if the search was illegal.</p>
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<p>If the weapon is considered inadmissible, is it returned to the suspect? If yes, would it also be returned even if it is of a type that the suspect is not legally allowed to own?</p>
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<p>Yes to both, though when it would be returned is subject to possible use in other investigations.   Additionally, while I don't know of any knife ban laws in the U.S., there are examples of contraband seized by arrest for a different offense was not returned when the initial offense was overturned on appeal, meaning the contraband evidence was no longer validly seized and thus that half of the case was overturned... but the defendant wasn't returned his drugs.</p>
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<p>Is the weapon permanently inadmissible for all future, or could it be used in a later court proceeding?</p>
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<p>No.  I'm starting to suspect I know the TV show and episode that inspired this question, but the search violated suspect 1's rights and thus was inadmissible for his trial.  However, if a second suspect was discovered as the evidence was developed, and the investigation lead to the knife (say... suspect 2 had access to suspect 1's car... like say... through his job at a car wash that suspect 1 was patronizing... and planted the knife in suspect 1's car to frame him) then the knife is admissible because of inevitable discovery rule.</p>
<p>Now, the TV Show I alluded too, and you'll forgive me as it's been a while, the events were that the cop pulled over suspect 1 for a valid reason (busted tail light, intentionally done by suspect 2 to get attention) and saw the knife on the backseat of the car, which is not a violation of search and seizure rules.  The bloody knife was in plain view and gave probable cause to arrest and search the entirety of the car.  If you leave evidence in a place where the officer can see it, they can seize it in a car at least.  Places like the glove box, under the seats, or the trunk would properly hide it and not allow the officer to search the car, but through the windows is just fine.</p>

<p>Under the Fourth Amendment, police need a reason both to stop a car and also to search it. (Under current precedent, they need &quot;reasonable suspicion&quot; to stop the car, and &quot;probable cause&quot; to search it.) If, as you say, the stop was &quot;unreasonable&quot; and the search was &quot;unlawful,&quot; both were unconstitutional. Under <a href="https://en.wikipedia.org/wiki/Exclusionary_rule" rel="nofollow noreferrer">the</a> &quot;exclusionary rule&quot; evidence gotten unconstitutionally cannot be used <em>directly</em> against the driver.</p>
<p>Furthermore, under the <a href="https://en.wikipedia.org/wiki/Fruit_of_the_poisonous_tree#:%7E:text=Fruit%20of%20the%20poisonous%20tree%20is%20a%20legal%20metaphor%20used,it%20is%20tainted%20as%20well." rel="nofollow noreferrer">doctrine</a> of the &quot;fruit of the poisonous tree&quot; any evidence gotten <em>indirectly</em> from an unconstitutional search also cannot be used against the driver. That is, the &quot;fruit&quot; of any further police work based on the excluded evidence is &quot;poisoned&quot; by its unconstitutional origins.</p>
<p>There are of course exceptions to both rules. Thus, if the stop was legal, the knife could be used as evidence if it was in &quot;plain view.&quot; Similarly, if the fruit of the poisonous tree has an &quot;independent&quot; source, or would &quot;inevitably&quot; have been discovered anyway, it can still be used.</p>
<p>As you can imagine, much of the law of searches and seizures has to do with cars. Many constitutional law texts even have sections on the law of cars. If you don't have one at hand, there are many summaries on line, like <a href="https://constitutioncenter.org/blog/cars-other-vehicles-and-the-constitution" rel="nofollow noreferrer">this</a>.</p>

<h2>For an alternative jurisdiction</h2>
<p><a href="/questions/tagged/australia" class="post-tag" title="show questions tagged &#39;australia&#39;" rel="tag">australia</a></p>
<p>The <em>Evidence Act</em> 1995 (Cth) and the similarly named acts in <a href="/questions/tagged/new-south-wales" class="post-tag" title="show questions tagged &#39;new-south-wales&#39;" rel="tag">new-south-wales</a>, <a href="/questions/tagged/victoria" class="post-tag" title="show questions tagged &#39;victoria&#39;" rel="tag">victoria</a>, <a href="/questions/tagged/tasmania" class="post-tag" title="show questions tagged &#39;tasmania&#39;" rel="tag">tasmania</a>, <a href="/questions/tagged/australian-capital-territory" class="post-tag" title="show questions tagged &#39;australian-capital-territory&#39;" rel="tag">australian-capital-territory</a> and <a href="/questions/tagged/northern-territory" class="post-tag" title="show questions tagged &#39;northern-territory&#39;" rel="tag">northern-territory</a> are all based on the model <a href="https://www.ag.gov.au/legal-system/publications/uniform-evidence-acts-comparative-tables" rel="noreferrer">Uniform Evidence Acts</a>. <a href="/questions/tagged/queensland" class="post-tag" title="show questions tagged &#39;queensland&#39;" rel="tag">queensland</a>, <a href="/questions/tagged/western-australia" class="post-tag" title="show questions tagged &#39;western-australia&#39;" rel="tag">western-australia</a> and <a href="/questions/tagged/south-australia" class="post-tag" title="show questions tagged &#39;south-australia&#39;" rel="tag">south-australia</a> do their own thing so we won't talk about them.</p>
<p>&quot;Improperly or illegally obtained evidence&quot; is dealt with in <a href="http://classic.austlii.edu.au/au/legis/cth/consol_act/ea199580/s138.html" rel="noreferrer">s138</a> which says it:</p>
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<p>... is not to be admitted unless the desirability of admitting the evidence outweighs the undesirability of admitting evidence that has been obtained in the way in which the evidence was obtained.</p>
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<p>This means that the judge has the discretion to allow the evidence if the interests of justice (in a global sense) are better served by admitting it. This discretion is unfettered except for the need to balance the &quot;desirability&quot; vs the &quot;undesirability&quot; - basically, are the interests of justice, taken globally, better served by admitting over excluding.</p>
<p>The act gives a non-exhaustive list of things the judge &quot;may&quot; consider:</p>
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<p>(a) the probative value of the evidence; and</p>
<p>(b)  the importance of the evidence in the proceeding; and</p>
<p>(c)  the nature of the relevant offence, cause of action or defence and the nature of the subject-matter of the proceeding; and</p>
<p>(d)  the gravity of the impropriety or contravention; and</p>
<p>(e)  whether the impropriety or contravention was deliberate or reckless; and</p>
<p>(f)  whether the impropriety or contravention was contrary to or inconsistent with a right of a person recognised by the <em>International Covenant on Civil and Political Rights</em>; and</p>
<p>(g)  whether any other proceeding (whether or not in a court) has been or is likely to be taken in relation to the impropriety or contravention; and</p>
<p>(h)  the difficulty (if any) of obtaining the evidence without impropriety or contravention of an Australian law.</p>
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