We know for sure because in some cases some other evidence were revealed, an example of that would be one of law enforcement officers telling the truth about thier partners either because they feel guilty or for some other personal reasons, but ya it happens all the time.
I am literally telling you that any random policeman can frame you pretty easily, just one pill of drug and you do a year in prison, you have to count on the integrity and honesty of everyone who has the power to frame you, you have no idea how scared people are when a police officer pull them over, you could end up doing a full a year in prison for "consuming drugs" and 5+ for selling it, if said officer has access to a large quantity of drugs they can put that in your car and you spend 5 good years in jail.
"extraordinary claims require extraordinary evidence", since this is someone's life and freedom, if the evidences are even remotely questionable -- they mean exactly nothing.
I'm glad that you understand the importance of evidence . What happens in your country is that you can't prove you are innocent . That's exactly what these cops are taking advantage of . It's your word against them .
Now imagine if these cops were wearing cameras . Imagine if there was a standard procedure that 2 cops had to search a car on opposite sides and film each other any moment so that no one of them could "plant" anything . Imagine if surveillance cameras existed in the place where traffic stops taking place so cops would know that their body camera videos are timestamped with the surveillance cameras that exist at the spot . Imagine if there were cameras in your car . Most of people will say that the bad state has cameras on policemen and cameras on road to invade their privacy , but these cameras can provide the evidence to prove that you are innocent .
So the problem is not that police is searching your car , but that the system is set up in such a way that it can be easily manipulated . Cops don't have accountability as no one can be certain if they act dishonestly , and by "default" a cop is serving the law so that makes him honest and you a criminal if they say so .
I think that in the cases you mention of cops telling the truth about their partners they would probably had some kind of evidence ( video , photo , recording etc ) . Usually when it's your word against 3 or 4 other guys , majority rules . So , that proves for another time what i say if you think of it .
Stop thinking that a society can work without rules both for public servants and citizens . Anarchy can't work , it will only lead to feudalism as human beings are mostly selfish . We need rules so there's accountability for our actions .
How do you know he is guilty? Whatever happened to presumption of innocence?
The onus is not on the accused to prove innocence - the onus is on the prosecution to prove guilt. And the onus is not on me to to open myself up to complete scrutiny by blockchain analysis and other government funded mass surveillance tools and prove that I have "nothing to hide".
Innocence is the default position. Privacy is the default position.
I guess i have pointed about the presumption of innocence above . If cops word is the only evidence then suspect is screwed .
These cops proved guilt even if it's fake , and the funny part is that we don't know who's right or wrong .
In blockchain you can prove if you're innocent or not . Your transactions are the evidence . If you decide to take the route of anonymity you deprive yourself from the evidence you have . Bitcoin ( as it was supposed to work ) provides you with a high level of privacy , but not anonymity . If you are looking to be an anon you should better move to other chains . Bitcoin by default will not provide that .