Can improperly gathered evidence be used to exonerate someone?
<p>There are many rules governing whether or not a particular piece of evidence can be introduced at trial.  Often, these rules are applied to prevent the <em>prosecution</em> from introducing evidence.  Do the same rules generally also apply to the defense?</p>

<p>For example, suppose officers obtain a DNA sample and send it off for testing. Later, it turns out they needed a warrant, but didn't get one, so the prosecution cannot use the test results. If the test shows the suspect is <em>not</em> the culprit, is the defense allowed to introduce this into evidence? Or are they bound by the same rules as the prosecution?</p>

<p>You're referring to the Exclusionary Rule, which bars the government's use of evidence it obtained in a bad-faith violation of the defendant's Fourth Amendment rights. It is typically only applied when a defendant objects to the use of the evidence, so it would not prevent a defendant from using that evidence if he wanted to. The government would not have standing to object to the defendant's use of the evidence.</p>

<p>If a defendant improperly obtained evidence, it could be subject to exclusion, as well, but there would likely be a heightened standard for doing so, given the defendant's Sixth Amendment right to a fair trial.</p>

evidence fourth-amendment admissibility