Hollywood has never been afraid to sacrifice realism for the sake of an entertaining story. And since pretty much every movie or TV show features the police in some way, we as an audience get fed a lot of total horseshit about how the law works and how cops operate in the USA.
But as most of us are on the outside of the judicial system (for the moment) we usually don't even realize that what we're being told is incorrect. So we just accept things like...
As Seen On:
The various CSI shows, Bones
There has been a murder. While the regular cops are all wasting time talking about "witnesses," "motives" and "evidence," the CSI team walks in and gets shit done. Within seconds they find a single hair, scan it with a green laser and discover the identity of the killer, saving countless lives with their ingenious magical science. Hell, the CSI team will even pack up their guns and go arrest the guy!
His one mistake was having hair.
Why it's Bullshit:
First, do you have any idea how much random DNA you are carrying on the soles of your shoes this very instant? A hair from that bank clerk across town, gum from a Pakistani cab driver and semen from an undetermined source are all probably crawling around down there, ready to be tracked through a crime scene.
Also, certain laboratory tests such as DNA samples, toxicology and blood reports can take weeks or even months to process, and when they do finally arrive, they are about as clear cut as the plot to The Phantom Menace.
"Wait, they're racing now?"
Also, while DNA criminal databases do exist, less than 1/10th of all criminals are a part of it. Having a bit of DNA doesn't mean shit unless they have something to compare it to.
That means the CSI stuff is less about finding the killer and more about making sure they have enough evidence to convict the guy they've already pinpointed as a suspect through old-fashioned police work.
CSI is really just another victim of bad Hollywood science, kind of an extension of their "computers are magic" philosophy. It's appealing to think that any problem--even crime--can be stopped cold by nothing but the power of science and human intellect. Add a few dead hookers and an exploding car to the mix and you have the recipe for television success, baby.
As Seen On:
Law and Order, Primal Fear, A Time to Kill
So things aren't looking so great: The cops caught you stabbing a priest, which you have found out is illegal in your city. Fortunately, your lawyer is Richard Gere, and the two of you combine to convince the jury that you are insane, and that the crime was carried out by one of your multiple personalities.
The man who defends himself has a fool for a lawyer. The man who hires Richard Gere has a sentient nose for a lawyer.
You get off, innocent by reason of insanity! Congratulations, a couple of months at the mental hospital and you'll be back on the streets!
Why it's Bullshit:
Obviously if the legal system had this kind of Get Out of Jail Free loophole, the prisons would be empty. In reality, the Insanity Defense is attempted in less than one percent of all legal cases, which essentially means that more people have tried to pin their crimes on aliens or their evil twin rather than their own basket case, shoelace-eating lunacy.
"No no, it was my brother, Larry Busey!"
Of that tiny fraction where the lawyer was even willing to try it, the defense is successful less than 25 percent of the time. Three states in the US don't even allow insanity as a defense.
Then, in that tiny, tiny fraction of cases where the guy "got off" because he convinced the court he was insane, he doesn't get to just go home. You get sent to a mental institution where you don't have a set sentence at all--they keep you as long as they see fit, which may be forever. You're there until "deemed safe to return to society", which according to the American Psychiatric Association is usually twice as long as the jail sentence would have been.
Hope you like white gowns and staph infections!
This has always been one of those situations where people simply want to believe the system is worse than it is. We can't escape the idea that the courts are too soft on the bad guys and that guilty people are running free left and right. Besides, what is insanity, anyway? Can't you say that anyone who willingly kills another human being is "insane"? Won't giving these guys a free pass based on a little craziness bring the whole system down?
Yes, it would. Which is why the courts don't do it.
As Seen On:Law And Order, Numb3rs
The hunt for the bad guy is on and his girlfriend/mother/dog might know where he's hiding. Jerry Orbach barges into their workplace demanding to know where said bad guy is laying low.
They don't want to cooperate with the cops, so they stay silent or develop sudden amnesia. Well that's just too damn bad, because Detective Briscoe says not cooperating with the police is called obstruction of justice and that'll get you a minimum of five years of rapetastic jail time.
"Starting to remember where your dad is now, Timmy?"
Why it's Bullshit:
Specifically, the 5th Amendment makes it bullshit. We, on the whole, don't really understand the 5th Amendment, because it has a really shitty marketing department and today is virtually synonymous with fat union gangsters hiding behind it like RoboCop is chasing them. Somebody "taking the 5th" means they're guilty, right?
Not everyone who gets arrested is an Italian-American stereotype.
No, it means under no circumstances can you be coerced into being a witness against yourself. And, since at the moment they speak to you, you don't know if you're a suspect or not, that means you always have the right to not talk to the police.
Now, obstruction of justice is a real thing, and it can be charged when you lie to the cops, destroy evidence or otherwise intentionally fuck up their investigation. But simply refusing to talk to them is not one of those things.
Note, however, that police do have the right to ask you to identify yourself in many states, in which case you do have to tell them who you are. And you do have to give them real answers (see the 1972 Supreme Court case Nebraska vs Heywood Jablome).
As Seen On:Rush, Deep Cover, Monk
An undercover police officer is meeting with a big time kingpin who wants to purchase some drugs/prostitutes in one the biggest drug/prostitution stings in years. It took months to establish the officer's rep on the streets all for this moment... and just then the kingpin asks the fatal question: "Are you a cop?"
The officer has no choice but to identify himself as a member of the police force and the entire operation goes to hell.
"It's OK, we actually knew the whole time."
Why it's Bullshit:
This is one of those tension-building devices in undercover cop movies (ie there's a tense scene in the Laurence Fishburne movie Deep Cover where he's forced to answer "yes" when asked the "are you a cop" question, then play it off as sarcasm) but even if asked directly, police officers have no obligation to blow their cover and get shot in the balls.
This makes sense if you think about it, since if that were really the rule there would be no sting operations whatsoever. Even the dumbest crackhead would remember to always ask his new supplier if he is a cop before each purchase.
Likewise for prostitution stings where the police pose as customers, then slap on the cuffs as soon as there's talk of blowjobs for cash. No, it's not entrapment, ladies.
Legally, it can't be entrapment without Sean Connery.