# Cops 'printing' cars **URL:** \ **Category:** Factual Questions\ **Created:** [September 7, 2013, 3:43am UTC](https://boards.straightdope.com/t/cops-printing-cars/668228 "2013-09-07T03:43:33Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Unintentionally\_Blank](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/unintentionally_blank/32/5418_2.png) [@Unintentionally\_Blank](https://boards.straightdope.com/u/Unintentionally_Blank)\ **Post date:** [September 7, 2013, 3:43am UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/1 "2013-09-07T03:43:33Z")
A coworker mentioned a little tidbit the other day and I figured I’d bring it over here for fact checking. He stated that any time a Police Officer pulled a car over, it was procedure to touch the vehicle. The reasoning being: If things went bad, there would be latent prints tying the car to the incident. Truth? Fiction? Something in-between? ---
**Author:** ![chacoguy](https://avatars.discourse-cdn.com/v4/letter/c/50afbb/32.png) [@chacoguy](https://boards.straightdope.com/u/chacoguy)\ **Post date:** [September 7, 2013, 3:58am UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/2 "2013-09-07T03:58:24Z")
I’ve seen it done; firmly and steadily pressing all the fingers onto the trunk. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [September 7, 2013, 1:59pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/3 "2013-09-07T13:59:55Z")
Yes, it’s a standard practice that is taught at many acadamies and agencies across the country. Whether it has ever come in handy or helped solve a crime is a completely other thing. But it’s still practiced, regardless. If you pay close attention the next time you’re watching COPS, you’ll occassionally see an officer do it. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [September 7, 2013, 2:13pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/4 "2013-09-07T14:13:14Z")
Here is a training video where the officer explains the technique. He also includes the second reason (which I purposely excluded from my previous post because it is even more worthless, but it is in fact a reason often repeated). It is to ensure the trunk is closed so that nobody can jump out of it and ambush the cop. But that’s just ridiculous since almost every car on the road has the ability to open the trunk from the inside now. So a fully closed trunk would not prevent this. [![]( " - YouTube") ](https://www.youtube.com/watch?v=1tU6c4KG6vs) ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [September 7, 2013, 2:43pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/5 "2013-09-07T14:43:51Z")
I think about this practice when I watch _Perry Mason_ and Lt. Tragg positively identifies a murder weapon because “it has my mark.” ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [September 7, 2013, 4:20pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/6 "2013-09-07T16:20:05Z")
As the others say it is a technique that is used by some. I personally don’t don’t do it and I have never heard of of a time when it came in handy. Trunk releases are controlled by the driver and by the time I get up to the car I have already called out the plate to dispatch. And I’m on tape. Having my prints on the car does nothing helpful as far as I can tell. Its more because some old-timers once said thats what you are supposed to do. We don’t use six shooters any more either. there is no need to continue with tactics from a bygone era. ---
**Author:** ![Kenm](https://avatars.discourse-cdn.com/v4/letter/k/bc79bd/32.png) [@Kenm](https://boards.straightdope.com/u/Kenm)\ **Post date:** [September 7, 2013, 4:28pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/7 "2013-09-07T16:28:00Z")
> [@KneadToKnow](#): > > I think about this practice when I watch _Perry Mason_ and Lt. Tragg positively identifies a murder weapon because “it has my mark.” I wonder how he made it to the lofty position of police lieutenant despite being unable to write. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 7, 2013, 5:22pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/8 "2013-09-07T17:22:57Z")
> [@Loach](#): > > As the others say it is a technique that is used by some. I personally don’t don’t do it and I have never heard of of a time when it came in handy. Trunk releases are controlled by the driver and by the time I get up to the car I have already called out the plate to dispatch. And I’m on tape. Having my prints on the car does nothing helpful as far as I can tell. Its more because some old-timers once said thats what you are supposed to do. We don’t use six shooters any more either. there is no need to continue with tactics from a bygone era. I’ve seen cops do it. In fact I looked it up online a few months ago when a cop did it in front of my house. Here’s the scenario that makes sense to me: You pull someone over, touch their brake light, as you get up to the door, they take off (maybe even hitting you). After they’ve lost you and have some time, they swap plates with another similar car. You pull that car over because the tags match, but release them due to a solid alibi for the car’s whereabouts. Later, someone tracks down the original car, the original occupants and find your finger prints on the brake light, which helps to prove it was the same car from earlier. Now, likely they’d only go through all this trouble if the officer was injured so it’s a pretty narrow set of circumstances, but all it requires is touching the back of the car. It’s such a small thing to do, so why not. No paperwork, no extra leg work, literally just lifting your hand. Anyways, the moral of the story is, if you run down a cop, be sure to wipe down the back of your car afterwards. Having said all that, I wonder how many times it’s actually come in helpful. OR, I wonder how many times it would have come in helpful, but the fingerprints weren’t there. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [September 7, 2013, 6:11pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/9 "2013-09-07T18:11:02Z")
Even without a deliberate effort to obliterate fingerprints, though, they’re not going to stay readable for long, especially not for something that gets out and about in the environment like a car does. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [September 7, 2013, 6:18pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/10 "2013-09-07T18:18:10Z")
> [@Kenm](#): > > I wonder how he made it to the lofty position of police lieutenant despite being unable to write. What I wanted to know was why such an old man was still working, only a lieutenant and utterly incompetent. Did he ever get anything right the first time? ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [September 7, 2013, 6:26pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/11 "2013-09-07T18:26:32Z")
> [@The\_Second\_Stone](#): > > What I wanted to know was why such an old man was still working, only a lieutenant and utterly incompetent. Did he ever get anything right the first time? Well, consider the batting average of the district attorney. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [September 8, 2013, 5:47am UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/12 "2013-09-08T05:47:32Z")
> [@KneadToKnow](#): > > Well, consider the batting average of the district attorney. Hey Ham Burger only lost on Sunday (I think ?) nights. He won the rest of his cases. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [September 8, 2013, 11:33am UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/13 "2013-09-08T11:33:41Z")
I thought this was going to be about cutting-edge applications for 3D printers. ☹ ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [September 8, 2013, 3:01pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/14 "2013-09-08T15:01:36Z")
> [@OldGuy](#): > > Hey Ham Burger only lost on Sunday (I think ?) nights. He won the rest of his cases. Saturday, but full marks. 🙂 ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [September 8, 2013, 3:35pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/15 "2013-09-08T15:35:12Z")
I wonder how much of it comes down to “Fuck you, Mr. Shiny Porsche owner - _nyah!_” 🙂 ---
**Author:** ![Kenm](https://avatars.discourse-cdn.com/v4/letter/k/bc79bd/32.png) [@Kenm](https://boards.straightdope.com/u/Kenm)\ **Post date:** [September 8, 2013, 3:44pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/16 "2013-09-08T15:44:48Z")
> [@njtt](#): > > I thought this was going to be about cutting-edge applications for 3D printers. ☹ I want a 3D printer that will make [**Tragg’s hat**](https://www.google.co.uk/search?lr=&cr=&safe=images&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&q=tragg%20lieutenant&sa=N&tab=wi&ei=zJksUoL6B9GQyQHwt4Ew&biw=1063&bih=603&sei=TposUsq_A6uyygHrzYCQCA#facrc=_&imgrc=E_ULdE6QslblRM%3A%3BmQn1Nvz4TbbccM%3Bhttp%253A%252F%252Fwww.wearysloth.com%252FGallery%252FActorsC%252Ftve3424-19580503-263.gif%3Bhttp%253A%252F%252Fwww.aveleyman.com%252FActorCredit.aspx%253FActorID%253D3424%3B320%3B240). ---
**Author:** ![UltraVires](https://avatars.discourse-cdn.com/v4/letter/u/ecccb3/32.png) [@UltraVires](https://boards.straightdope.com/u/UltraVires)\ **Post date:** [September 8, 2013, 3:49pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/17 "2013-09-08T15:49:06Z")
> [@KneadToKnow](#): > > Well, consider the batting average of the district attorney. Not to hijack, but how did that guy ever keep his job? Charging innocent people with murder every single time! ---
**Author:** ![pkbites](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pkbites/32/204_2.png) [@pkbites](https://boards.straightdope.com/u/pkbites)\ **Post date:** [September 8, 2013, 4:11pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/18 "2013-09-08T16:11:54Z")
> [@Bear\_Nenno](#): > > Here is a training video where the officer explains the technique. He also includes the second reason (which I purposely excluded from my previous post because it is even more worthless, but it is in fact a reason often repeated). It is to ensure the trunk is closed so that nobody can jump out of it and ambush the cop. But that’s just ridiculous since almost every car on the road has the ability to open the trunk from the inside now. So a fully closed trunk would not prevent this. But that is why it was being taught. Since 1982 I was taught to lightly push the trunk to make sure it’s closed. They’re still teaching this, with the advice about the trunk being able to be opened from the inside or with a remote. A couple of years ago during an in-service training session the instructor had a suspect at a traffic stop scenario open the trunk from inside the car to see if the officer would hear the _click_. > [@jtgain](#): > > Not to hijack, but how did that guy ever keep his job? Charging innocent people with murder every single time! 😛 No kidding. I always wondered how that incompetent SOB kept getting elected D.A.! ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [September 8, 2013, 10:20pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/19 "2013-09-08T22:20:05Z")
> [@KneadToKnow](#): > > I think about this practice when I watch _Perry Mason_ and Lt. Tragg positively identifies a murder weapon because “it has my mark.” That’s a little different. Back then, when something was taken into evidence, someone would mark it. This would preserve the chain of evidence so that the defendant can’t say “they got the wrong gun.” ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [September 9, 2013, 12:09pm UTC](https://boards.straightdope.com/t/cops-printing-cars/668228/20 "2013-09-09T12:09:24Z")
> [@pkbites](#): > > But that is why it was being taught. Since 1982 I was taught to lightly push the trunk to make sure it’s closed. They’re still teaching this, with the advice about the trunk being able to be opened from the inside or with a remote. > > A couple of years ago during an in-service training session the instructor had a suspect at a traffic stop scenario open the trunk from inside the car to see if the officer would hear the _click_. Well? Did they hear it?