Explanatory vs Exploratory evidence in legal proceedings In academia, there is an important distinction between exploratory analyses of data and confirmatory analyses. Careers have been ruined by researchers passing off the one as the other. Since the gathering and introduction of evidence in legal proceedings is quite similar to the procedure in scientific circles, I was wondering if there are rules and procedures to safeguard against potential abuse (deliberate or accidental) of exploratory evidence. A simple legal analogue of the case above might be, for example: Alice is picked up due to a separate investigation of her drug dealer whose phone contained drug-related texts to Alice. Her phone is confiscated, and its contents dredged for signs of anything and everything. The phone is found to contain illegal pornographic content. Questioning of friends and relatives reveal that they have a suspicion that Alice might be involved in the creation of illegal pornographic content. Contrast this with Bob, whose friends and relatives approach police with a suspicion that Bob might be involved in the creation of illegal pornographic content. Bob is arrested and his phone is searched for the illegal content hypothesized by his friends and family, which is found to reside on Bob's phone. In both scenarios, the evidence against Alice and Bob is ostensibly identical with the single exception that the evidence against Bob is confirmatory. Thus, although the situation looks grim for both, since the evidence against Bob is confirmatory, it might be considered stronger. Would anyone be inclined to press such a distinction in court proceedings?
In US law, there was, as far as the question indicates, no probable cause to search her phone at all, Therefore (unless there is some cause not mentioned in the question), any such search is illegal, and any evidence found in such a search, or that is found as an indirect result of such a search (pointers toward it are found in the search, and followed) would not be admissible in any criminal case against Alice. In the case of Bob, if his friends and family approach the police or other authority with a vague suspicion that Bob might be involved in the creation of illegal content That will probably not constitute probable cause for an arrest of Bob or a search warrant for his phone. Unless the accusation does prove to constitute probable cause, any evidence found during such a search would not be admissible against Bob in a criminal case. In practice, most US police would not undertake either search without better evidence than is described in the question. But some police will overstep the lines, which is what the US exclusionary rule is for. Legal procedure does not as far as I know make a distinction between "exploratory" and "confirmatory" evidence. Instead, evidence is either admissible or not. The rules for when evidence is admissible are quite complex, and vary by jurisdiction. Some of them are more traditional than logical, and some of them are addressed to particular problems that have arisen in particular circumstances. But the US Fourth Amendment protections against unreasonable searches, and the requirement of probable cause before search or arrest warrants are issued, serves some of the same purpose. Other countries have different rules, but many of them restrict the authorities to some extent from making arbitrary searches with no initial evidence. Response to the Revised Question As the question has been edited, there seems to be fairly clear probable cause to search Alice's phone, and if clear evidence of "illegal pornographic content" presumably actually child pornography, as no other kind is illegal simply to posses) is found, she can be brought to trial and perhaps convicted. The mere "suspicion" of Alice's "friends and relatives" would add little and mi8ght well not even be admissible. The facts, if any, on which those suspicions are based might be admissible, one cannot tell from the summary in the question. The case against Bob, however, remains weak. Indeed there still seems to be no probable cause either to arrest Bob nor to se3arch his phone, and the results of any search that was done would not be admissible. Probably none would be done without more evidence. The OP wrote: Thus, although the situation looks grim for both, since the evidence against Bob is confirmatory, it might be considered stronger. Not so, the case against Bob is weaker, indeed so weak that an arrest would be unlikely, and if one were made, the case would likely be dismissed before going to trial, assuming no more evidence than was included inn the question. The evidence prior to the search seems to consist only of vague suspicion not supported by any actual evidence, and so there is nothing to confirm, and no valid search would occur. That suspicion of Bob came before the search, and the search is thus "confirmatory" is not relevant. The question is, what evidence against each defendant is admissible, and does the totality of the admissible evidence amount to "proof beyond a reasonable doubt" no matter what order it was discovered in, or what idea was in the minds of the investigators, provided that they were acting lawfully so that their findings are admissible.
The burden for proving claims in civil actions is "preponderance of evidence," i.e., merely that "more than 50% of the evidence favors a conclusion." However, the standard for conviction of any crime is "beyond a reasonable doubt." I.e., if the defense can raise reasonable doubt about one's guilt then the defendant should be acquitted. There is quite a bit of space between the two standards, which is compounded by prosecutorial discretion to even bring criminal charges.
Whether they are admissible as evidence is up to the trier of law The “trier of law” (judge) decides what evidence is admissible according to the rules of evidence. Documents of most kinds are not admissible on their own (exceptions include “business” documents like invoices and receipts). To be admissible, someone (presumably you) has to testify as to what they are, how they were created and maintained and why they are relevant before the judge will decide if they will be accepted as evidence. Whether they prove anything is up to the trier of fact Evidence is not proof The “trier of fact” (jury in a jury trial, judge in a bench trial) decides what weight to give to any and all evidence presented. They may accept the testimony about the documents or they may reject it. If presented with conflicting testimony they have to decide which they prefer. Judges have to give reasons for their decisions which can be appealed. Juries don’t. Files that are readily changeable are likely to be given less weight than files which have a verifiable audit trail. For example, if you kept your .docx files in a GitHub repository they will be stronger evidence than those kept on a local hard drive.
The question says: Callahan used torture to get the location of the hostage out of the suspect, and information acquired by torture is not admissible as evidence. In general, evidence obtained by torture is indeed not admissible in US courts. This is particularly true when the person doing the torture is a police officer. If it is done by a private citizen, with no prompting or encouragement by the police or any part of the government, different rules may apply. See Brown v. Mississippi, 297 U.S. 278 (1936) for the inadmissibility of confessions obtained through torture or physical coercion. The Mapp decision, cited below, would have extended this to information or evidence obtained via torture. The question asks: It was not merely information what Callahan acquired, but the physical body of the victim. Doesn't that change anything? No. If the evidence was obtained unlawfully, then the evidence so obtained and all other evidence or information indirectly obtained through the unlawful act is inadmissible. This is the &quot;Fruit of the poisonous tree&quot; doctrine. It applies just as much to physical evidence as to a confession. &quot;Fruit of the poisonous tree&quot; doctrine is an extension of the &quot;exclusionary rule&quot; and like the basic rule, is intended to deter unlawful actions on the part of law enforcement and government generally, and to ensure that the courts are not complicit in such unlawful actions. The rule was first fully established in US Federal courts in Weeks v. United States, 232 U.S. 383 (1914) although versions of the rule go back before the founding of the United States. The rule was applied to the states in Mapp v. Ohio, 367 U.S. 643 (1961) although some states applied a version of the rule even before the Weeks decision. There are exceptions, however, notably &quot;inevitable discovery&quot;. That means if other, lawful, investigations already underway would certainly have uncovered the same evidence, then it may be admissible. Another similar exception is the &quot;Independent source doctrine&quot;. This says that when the same evidence is later obtained independently from activities untainted by the initial illegality, it may be admissible. See Nix v. Williams, 467 U.S. 431 (1984), for both of these exceptions. There is also a good-faith exception where a warrant was obtained on invalid grounds but used in good-faith by offers who thought it valid. I do not see that any of these exceptions would apply in the situation described in the question. It does not matter how &quot;clear&quot; the evidence may be. If it is obtained unlawfully, and no exception applies, it will not be admissible. The question asks: In case of the hideout and the rifle, is such a clear evidence still inadmissible? Can't the &quot;hot pursuit&quot; rules be applied? He didn't have time for a warrant, he was running against the clock. The doctrine of&quot;hot pursuit&quot; alone does not justify entering a private dwelling without a warrant, but there are a number of exceptions to the warrant requirement, one of which &quot;Exigent Circumstances&quot; is one, or rather a group of relates exceptions. In Missouri v. McNeely, 569 U.S. 141 (2013), the Supreme Court wrote in its opinion, &quot;A variety of circumstances may give rise to an exigency sufficient to justify a warrantless search, including law enforcement's need to provide emergency assistance to an occupant of a home . . . engage in “hot pursuit” of a fleeing suspect . . . or enter a burning building to put out a fire and investigate its cause.&quot; Thus “hot pursuit” can be an exigent Circumstance and justify a warrentless entry, but this will depend on the precise facts of the case. It is not clear that the circumstances described in the question would qualify. The question asks: even if they decide not to press charges because they are afraid they can't win the trial, can't they at least put the suspect under surveillance? Legally, they probably can. Not even probable cause is required to continue an investigation, or to place a suspected criminal under surveillance There might be reasons other than the law of evidence not to use surveillance, for example if the police fear that the suspect will observe the surveillance and thus be alerted. But this seems like a place where the movie plot may have been unrealistic.
For the offense of receiving stolen goods, "tracing" does not usually apply. It must be the actual good stolen and not proceeds of illegal activity. Tracing could come up in an effort to impose a "constructive trust" (usually by a private party) or "civil forfeiture" (usually by law enforcement) on the proceeds of embezzlement or fraud, for example. Tracing in this circumstance is governed by broad considerations of equity law and are highly fact specific. The methods are fairly ad hoc and mostly come down to rules of reason. For example, a court might find that anything clearly purchased with clean assets that were not comingled with dirty assets are not subject to forfeiture or a constructive trust, but that the entire amount of comingled assets might be subject to forfeiture or a constructive trust up to the total amount less the amount of clean assets which were comingled. This issue came up in the U.S. Supreme Court of Luis v. United States in 2014 over whether clean funds of someone subject to fraud liability could be frozen to protect the solvency of someone who may have already squandered the dirty funds when the defendant wants to use the clean funds for an expensive legal defense of the case (SCOTUS said that assets purely traceable to clean sources can't be tied up so as to prevent them from being used in a legal defense of the case.) Tracing generally does not extend to a bona fide purchaser for value (i.e. someone with no knowledge of wrongdoing is paid fair market value for something or pays fair market value for an asset) of something from the person engaged in misconduct because there was no economic benefit from the transaction to either party's net worth. What if Bob offers a smaller sum of money to many people, small enough that Bob could easily afford to give such a gift to one person, but the combined cost of so many small gifts adds up to an amount bob couldn't/wouldn't have been able to afford without his supplementary income? Could someone argue that the gift they received from Bob came from his legal income, but the other gifts Bob made to others was due to Bob's illegal activities, by claiming Bob was likely to give a gift to them without the extra illegal income but not to the others etc? In this situation, the gifts would be a "fraudulent transfer" because absent his illegal assets, Bob would probably be insolvent (i.e. have debts in excess of his assets), and transfers made without receiving substantially equivalent value in exchange can be unwound by his creditors if he is insolvent himself within a certain number of years. His solvency at the time of the gift rather than tracing from legal or illegal income respectively, would be the relevant legal issue. Of course, if the amounts of the gifts were small, it might not be economic to sue for their return.
The Evidence Would be Admissible. Under the so-called &quot;good faith exception&quot; to the exclusionary rule the evidence would probably be admitted over Bob's objections in both cases mentioned in the question. Recent US court decisions have limited the exclusionary rule when police officers reasonably but mistakenly believe that a valid warrant exists, and find evidence acting under such an apparent warrant. However, if there is good evidence of intentional falsification by the police, the exception will probably not apply. As to the second case, where Bob is home and protests that an error is being made, police are not required to, and often do not, accept much that suspects or subjects of warrants say in their own defense. If anyone could simply claim there was an error and delay a warrant, perhaps giving time to dispose of evidence, many problems would result. However, the &quot;good faith&quot; exception only applies where the police reasonably and honestly believe that the warrant is valid, or that probable cause exists. If Bob says something such as: This warrant is for 1020 Anne street, where Alice Crook lives. But I live at 1050 Albert street. See the house number is 1050 right here. There must be a mistake. then a reasonable officer would probably double check the warrant, and if the officer unreasonably fails to do so, the search might later be suppressed. But this is going to be a very fact-sensitive inquiry, and none of the cases that I know of on the &quot;good faith exception&quot; rule are exactly on point for this situation. I cannot be sure how a court might rule in such a case. Leon and Evans Cases In United States v. Leon 468 U. S. 897, the US Supreme Court created a &quot;good faith exception&quot; to the exclusionary rule. In that case the Court held that when officers make an objectively reasonable, good faith decision to rely on a warrant later held to be invalid, the exclusionary rule does not apply, and evidence found during a search under such a warrant, or in the course of an arrest under such a warren, is admissible. The basic logic is that when the invalid warrant was the result of an honest mistake, suppressing the evidence would have no deterrent effect on future similar mistakes, as no one intended to make them in any case. In Arizona v. Evans 514 U. S. 1 (1995), this rule was extended to officer who rely in good faith on information mistakenly provided by Court employees. The underlying logic is much the same. Herring v. United States In Herring v. United States, 555 U.S. 135 (2009) this exception was further extended to officers who acted in good faith on the mistaken information of other officers. Evidence found in a search incident to an arrest, although there was no valid arrest warrant or other probable cause, was not suppressed. In this case a warrant had been issued but later recalled. however this recall was somehow not properly entered into the database of warrants maintained by a sheriff's office. When a nearby jurisdiction called to ask if there was an outstanding warrant on Herring, they were told that there was one. Herring was arrested, and drugs and an unlawful firearm found. Minutes later the officers were told that the arrest warrant was not valid. Herring was convicted based on the evidence from the search, and the US Supreme court upheld the conviction. The court wrote in Herring: When a probable-cause determination was based on reasonable but mistaken assumptions, the person subjected to a search or seizure has not necessarily been the victim of a constitutional violation. The very phrase “probable cause” confirms that the Fourth Amendment does not demand all possible precision. And whether the error can be traced to a mistake by a state actor or some other source may bear on the analysis. For purposes of deciding this case, however, we accept the parties’ assumption that there was a Fourth Amendment violation. The issue is whether the exclusionary rule should be applied. The fact that a Fourth Amendment violation occurred—i.e., that a search or arrest was unreasonable—does not necessarily mean that the exclusionary rule applies. Illinois v. Gates, 462 U. S. 213, 223 (1983). Indeed, exclusion “has always been our last resort, not our first impulse,” Hudson v. Michigan, 547 U. S. 586, 591 (2006), and our precedents establish important principles that constrain application of the exclusionary rule. ... the exclusionary rule is not an individual right and applies only where it “ ‘result[s] in appreciable deterrence.’ ... When police act under a warrant that is invalid for lack of probable cause, the exclusionary rule does not apply if the police acted “in objectively reasonable reliance” on the subsequently invalidated search warrant. 468 U. S., at 922 (Leon). We (perhaps confusingly) called this objectively reasonable reliance “good faith.” In a companion case, Massachusetts v. Sheppard, 468 U. S. 981 (1984), we held that the exclusionary rule did not apply when a warrant was invalid because a judge forgot to make “clerical corrections” to it. ... in Evans, 514 U. S. 1, we applied this good-faith rule to police who reasonably relied on mistaken information in a court’s database that an arrest warrant was outstanding. We held that a mistake made by a judicial employee could not give rise to exclusion for three reasons: The exclusionary rule was crafted to curb police rather than judicial misconduct; court employees were unlikely to try to subvert the Fourth Amendment; and “most important, there [was] no basis for believing that application of the exclusionary rule in [those] circumstances” would have any significant effect in deterring the errors ... the abuses that gave rise to the exclusionary rule featured intentional conduct that was patently unconstitutional ... ... To trigger the exclusionary rule, police conduct must be sufficiently deliberate that exclusion can meaningfully deter it, and sufficiently culpable that such deterrence is worth the price paid by the justice system. ... In Franks v. Delaware, 438 U. S. 154 (1978), ... we held that police negligence in obtaining a warrant did not even rise to the level of a Fourth Amendment violation, let alone meet the more stringent test for triggering the exclusionary rule. ... We do not suggest that all recordkeeping errors by the police are immune from the exclusionary rule. In this case, however, the conduct at issue was not so objectively culpable as to require exclusion. In Leon we held that “the marginal or nonexistent benefits produced by suppressing evidence obtained in objectively reasonable reliance on a subsequently invalidated search warrant cannot justify the substantial costs of exclusion.” 468 U. S., at 922. The same is true when evidence is obtained in objectively reasonable reliance on a subsequently recalled warrant. If the police have been shown to be reckless in maintaining a warrant system, or to have knowingly made false entries to lay the groundwork for future false arrests, exclusion would certainly be justified under our cases should such misconduct cause a Fourth Amendment violation. See the Wikipedia article on Herring and this Leagal Information Institute article on the case
Is mere accusation without evidence other than testimony of the accuser, grounds for arrest in the UK? It depends on the circumstances, especially when dealing with non-recent allegations where independent and corroborative evidence may be difficult to locate and/or recover, but in my experience it is very rarely an option to arrest soley on the say-so of one complainant unless there is a compelling reason to do so. It's also fraught with potential risks - Operation Midland being a prime example of when it can go horribly wrong. Also, no-one can &quot;call the police and have someone arrested&quot; in the united-kingdom - the police are under a duty to carry out a &quot;proportionate investigation&quot; in to allegations of crime and then make their own minds up on how to proceed based on the available intelligence and evidence. Focussing on england-and-wales, the most commonly used power of arrest* is at s.24 of the Police and Criminal Evidence Act 1984 which, along with PACE Code G, requires an officer to: Reasonably suspect that an offence is being, has been or will be committed. On a scale of 0 to 10 - with 10 being total knowledge and 0 being no opinion at all - suspicion may be as low as 2 or 3 whereas belief starts at 7 or 8. And reasonably believe an arrest is necessary. One commonly used mnemonic for the Necessity Test under s.24 is: ID COP PLAN: Investigation - prompt and effective investigation of offence or conduct Disappearance - prevent prosecution being hindered by disappearance of a person Child / Vulnerable person - protection of Obstruction of highway Physical injury to themselves or someone else Public (in)decency Loss or damage to property Address not know Name not known I cannot say why the officer did not make an arrest in the OP's case. I surmise that he did not deem it necessary based on the above mandatory criteria but rather considered that a voluntary attendance interview would be the most appropriate course of action given the circumstances and information available to him at the time. *There are other statutory and common-law powers of arrest, but they all follow the same procedures as above
A lawyer for either party can claim, during argument, that an adverse witness is not credible, for any reason or none. Often the lawyer will point to matters disclosed during cross-examination, claiming that they are contradictions, show bias, or otherwise indicate lack of credibility. Or the lawyer could point to elements of the primary testimony which the lawyer claims are implausible. If there has be evidence of a prior conviction, the lawyer could refer to this. A lawyer may in general ask a witness about prior convictions. Criminal convictions are generally matters of public record, and can be researched. It is not usual to present reputation or credibility witnesses for any person except the defendant, and failure to do so, even for the defendant, does not lead to any automatic assumption of lack of credibility. Not does the appearance of such a witness grant an automatic assumption of credibility. But a lawyer may point out reasons for thinking a witness not credible. Ultimately it is up to the finder of fact, often a jury, to decide what weight to give the testimony of each and every witness, based on the impression that testimony made, as well as any argument from the lawyer. This is one reason why courts are reluctant to overturn factual assessments by a jury: the reviewing court does not see and hear the manner of a witness and what it may indicate about credibility.