Is it legal for police in California to use a hidden microphone? Is it legal for police in California to record suspects via a hidden microphone in police vehicles? If so, how can the information obtained be used?
The police are probably exempt from liability and the evidence is probably admissible pursuant to California Penal Code § 633 which states (referencing the two party consent statutes): (a) Nothing in Section 631, 632, 632.5, 632.6, or 632.7 prohibits the Attorney General, any district attorney, or any assistant, deputy, or investigator of the Attorney General or any district attorney, any officer of the California Highway Patrol, any peace officer of the Office of Internal Affairs of the Department of Corrections and Rehabilitation, any chief of police, assistant chief of police, or police officer of a city or city and county, any sheriff, undersheriff, or deputy sheriff regularly employed and paid in that capacity by a county, police officer of the County of Los Angeles, or any person acting pursuant to the direction of one of these law enforcement officers acting within the scope of his or her authority, from overhearing or recording any communication that they could lawfully overhear or record prior to January 1, 1968. (b) Nothing in Section 631, 632, 632.5, 632.6, or 632.7 renders inadmissible any evidence obtained by the above-named persons by means of overhearing or recording any communication that they could lawfully overhear or record prior to January 1, 1968. Cal. Penal Code Ann. § 633. See, e.g., People v. Clark, 372 P.3d 811 (Cal. 2016) (Tape recordings of defendant's telephone conversations with sister of murder victim admitted at murder trial did not violate state Invasion of Privacy Act, since sister was acting pursuant to direction of police inspector acting within the scope of his authority.); Armenta v. Superior Court of Santa Barbara County, 61 Cal.App.3d 584 (1976) (Section 632 was not violated when sheriff's deputies recorded conversation between enrollee in methadone maintenance program and fellow enrollee who was acting as undercover informant, since prohibition under that section does not apply to police informants); People v. Collins, 182 P.2d 585 (Cal. App. 1947) (Testimony of district attorney's stenographer, who listened in and took notes over concealed microphone equipment, was properly admitted.) The year 1968 is when California adopted its statutory invasion of privacy law. Prior to that point and still today, the constitution's protection of privacy and requirement for warrants to do a wiretap is much narrower than the requirement under California's two party consent statute (but for Section 633 above). I also doubt that there is a reasonable expectation of privacy while in custody in the back of a patrol car or while otherwise arrested. There is definitely no expectation of privacy in that situation if the suspects have been given Miranda warnings.
There is no common law offence of electronically recording a private place/activity, but many jurisdictions have legislation that makes it an offence: e.g. Surveillance Devices Act 1999 (Vic), s 7. Whether evidence collected through illegal surveillance is admissible will depend on the legislation in each jurisdiction. For example, in Victoria, such evidence is inadmissible unless the court decides that admitting the evidence is sufficiently desirable: Evidence Act 2008 (Vic), s 138. This discretion reflects 'the fundamental dilemma... between the public interest in admitting reliable evidence (and thereby convicting the guilty) and the public interest in vindicating individual rights and deterring misconduct and maintaining the legitimacy of the judicial system': Australian Law Reform Commission (2006) 'Uniform Evidence Law', [16.84].
Recording other people without consent is a crime (§ 201 StGB). But so is threatening other people with violence (§ 241 StGB). Secret recordings and other acts can still be legitimate if they are necessary and appropriate to deflect harm (§ 34 StGB), similar to how hurting someone can be legitimate if you're acting in self-defense. If you're prosecuted for this, it will be up to the court to determine if your act was necessary and proportionate. But regardless of what you did, your recording can be used as evidence against the ex-roommate. German criminal law does not generally exclude illegally acquired evidence. The main risk of disclosing this recording is that you are also providing evidence against yourself for possible wiretapping charges (which may or may not be punishable as discussed above).
If you wrote for example "I had thoughts about taking the axe from my garage and decapitating my neighbour", and your neighbour read that, he would reasonably be worried and contact the police. I would take that as a death threat, and the death threat is by itself illegal. There would be some range where I could claim that you were making a death threat and making excuses to avoid legal responsibility. You can have all the thoughs you like, you can write them into your private diary where nobody can read them, but as soon as you publish it, it becomes "speech" and some speech is illegal.
It is definitely illegal in Russia as well, but the police will do nothing. Previous activity of this group included forcefully attacking people who tried to speak to a girl who disliked it and handling over such people to police to get fined "for hooliganism". Usual practice in Russia is to beat the people whom the random girls around dislike. This group stepped a bit further, involving police. They use illegal or questionable methods, definitely. But they use them in a manner that people would be unlikely to complain to police because they themselves either did something illegal or public opinion is not on their side. The police usually will do nothing even with much more serious violations, like beating somebody.
Let's break it apart: The police has an union or charity. That's legal in most jurisdictions. The union or charity accepts donations from non-police. Also legal in most jurisdictions. The union communicates who the donors are. Generally legal in most jurisdictions. Keeping it secret would be just as problematic. Police officers have some discretion if and how they charge incidents. That's just common sense. Otherwise you get cases like 8-year-olds being arrested. (You get those anyway when the police don't use their discretion, or if the laws are too rigid.) Police officers let themselves be influenced by the donor card in how they apply their discretion. That's usually illegal on the part of the police officer. The Brits use the catchphrase 'without fear or favour.' But it is difficult to prove, even if it is systematic. The union issues donor cards to facilitate the effects of the previous bullet point. That sounds at the very least unethical. Some might argue that it is organized corruption. On the other hand, you can assume that the police unions have some decent lawyers on staff, and that they made sure that the words on their cards are not blatantly illegal in the jurisdiction in question. It might take something like a whistleblower, a sting operation, or an internal affairs investigation to prove corruption.
There's no legal requirement in Canada or US that the police do anything to investigate a crime, so there's no requirement that they do anything specific to investigate a crime. If the police officers are satisfied by the witness accounts, or have some reason to think viewing surveillance recording wouldn't be useful they don't have to, either by law or policy. Note that ordinarily, police won't consider a physical altercation between two grown men a serious enough crime to warrant charges. If there was no serious injury and there wasn't a large discrepancy between the strength of the two men, police will often decline to lay charges even when they believe the evidence would sustain them. In this case the police may have decided it wasn't worth investigating further because it wasn't worth wasting the time of an already overloaded court system. The victim here still has legal options despite the lack action by the police. He can subpoena the video evidence if he wants to bring lawsuit for damages. In Canada, it's possible even to lay your own criminal charges in a private prosecution, although this much more expensive than a civil lawsuit.
A &quot;police car&quot; doesn't necessarily have a special legal status, so a police officer can theoretically drive a beat-up pickup truck and &quot;be legal&quot; (but not in Washington, see below). What matters is whether others have to give special attention to the vehicle. The pertinent question is, what are the requirements for being an authorized emergency vehicle. I'll give you Washington state law, and you can apply this to other states fairly easily. RCW 46.37.190(1) mandates that Every authorized emergency vehicle shall, in addition to any other equipment and distinctive marking required by this chapter, be equipped with at least one lamp capable of displaying a red light visible from at least five hundred feet in normal sunlight and a siren capable of giving an audible signal. (3) Vehicles operated by public agencies whose law enforcement duties include the authority to stop and detain motor vehicles on the public highways of the state may be equipped with a siren and lights of a color and type designated by the state patrol for that purpose. The state patrol may prohibit the use of these sirens and lights on vehicles other than the vehicles described in this subsection. Given these restrictions, a driver knows whether they must get out of the way, and whether they have to &quot;pull over&quot; (stop driving and get ready for a brief traffic detention). The manner of attachment of &quot;stuff&quot; on the outside of the vehicle falls under general state patrol safety rules, whereby for example you can't balance a rocking chair on the roof and speed down the highway. The state patrol has reasonable discretion to deem that a particular mode of attachment is &quot;unsafe&quot; – this won't be like building-code minutia. Duck tape would probably be deemed to be an insecure means of attachment. There can be some statutory provisions regarding use of private vehicles, for example RCW 46.37.185 allows green lights on firefighter's private care: Firefighters, when approved by the chief of their respective service, shall be authorized to use a green light on the front of their private cars when on emergency duty only. Such green light shall be visible for a distance of two hundred feet under normal atmospheric conditions and shall be of a type and mounting approved by the Washington state patrol. The use of the green light shall only be for the purpose of identification and the operator of a vehicle so equipped shall not be entitled to any of the privileges provided in RCW 46.61.035 for the operators of authorized emergency vehicles. Flashing blue lights are prohibited by WAC 204-21-230(c)(4) &quot;other than a law enforcement vehicle as defined in WAC 204-21-020&quot;, which is &quot;a publicly owned or leased vehicle operated by a law enforcement agency and which is used for the law enforcement functions of the agency&quot;. That means that in Washington, the town sheriff cannot use his personal car as a law enforcement vehicle. I expect there to be some variation on that point across the US. The lights-and-sirens law is what keeps ordinary people from putting lights and sirens on their vehicles.