# DNA gathering legal once arrested **URL:** \ **Category:** Great Debates\ **Created:** [June 3, 2013, 5:03pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046 "2013-06-03T17:03:46Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![sleestak](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sleestak](https://boards.straightdope.com/u/sleestak)\ **Post date:** [June 3, 2013, 5:03pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/1 "2013-06-03T17:03:46Z")
I didn’t see a thread on this which kinda surprised me. Anyhoo… It is now legal for the police to take a DNA sample of anyone who has been arrested. [Link](http://usnews.nbcnews.com/_news/2013/06/03/18722878-supreme-court-upholds-dna-swabbing-of-people-under-arrest?lite). Not sure where I stand on this. My gut instinct is that this is bad. However, the police get fingerprints and DNA is not a whole lot different as far as the use in identifying criminals goes. As an aside, it was an interesting split on the court. Slee ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [June 3, 2013, 5:25pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/2 "2013-06-03T17:25:07Z")
Yes, Scalia siding with the liberals. Generally speaking, I’ll lean towards a safer populace over individual rights wrt search. If this helps finger dangerous criminals that need to be taken off the streets then I don’t mind minor invasions of privacy. As they said it’s not flippantly performed like on just anyone ‘flying on an airplane’ but on those arrested with probable cause for a serious crime and it is non-surgical, minimally invasive. CNN further mentions concerns some have about using this to build a genetic profile that would be used outside of law inforcement. _Each has different procedures, but in all cases, only a profile is created. About 13 individual markers out of some 3 billion are isolated from a suspect’s DNA. That selective information does not reveal the full genetic makeup of a person and, officials stress, nothing is shared with any other public or private party, including any medical diagnostics._ ---
**Author:** ![LonghornDave](https://avatars.discourse-cdn.com/v4/letter/l/a87d85/32.png) [@LonghornDave](https://boards.straightdope.com/u/LonghornDave)\ **Post date:** [June 3, 2013, 6:30pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/3 "2013-06-03T18:30:16Z")
I think Scalia knocks it out of the park in his dissent. [Maryland v. King](http://www.supremecourt.gov/opinions/12pdf/12-207_d18e.pdf) How can it possibly be argued that taking DNA is for identification purposes and not crime solving purposes? ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [June 3, 2013, 6:32pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/4 "2013-06-03T18:32:39Z")
As I understand it, the key to Scalia’s argument is that taking fingerprints aids in identification of the suspect at the time of arrest. Taking DNA does not return results until much later, by which time identifying the suspect is generally no longer an issue. Hence, taking DNA does not aid the immediate need, but only a hypothetical future investigation. Basically, taking DNA is kind of a “precrime” thing. ---
**Author:** ![LonghornDave](https://avatars.discourse-cdn.com/v4/letter/l/a87d85/32.png) [@LonghornDave](https://boards.straightdope.com/u/LonghornDave)\ **Post date:** [June 3, 2013, 6:40pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/5 "2013-06-03T18:40:01Z")
> [@BrotherCadfael](#): > > As I understand it, the key to Scalia’s argument is that taking fingerprints aids in identification of the suspect at the time of arrest. Taking DNA does not return results until much later, by which time identifying the suspect is generally no longer an issue. Hence, taking DNA does not aid the immediate need, but only a hypothetical future investigation. > > Basically, taking DNA is kind of a “precrime” thing. Yes, here’s from the majority opinion. [QUOTE=Majority] The legitimate government interest served by the Maryland DNA Collection Act is one that is well established: the need for law enforcement officers in a safe and accurate way to process and identify the persons and possessions they must take into custody. [/QUOTE] In this case, the DNA testing did not take place until after arraignment months after the arrest. It seems fairly clear that it was not tested for identification purposes. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 3, 2013, 6:48pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/6 "2013-06-03T18:48:18Z")
This is a landmark decision. One that I think will change police procedures significantly. A National DNA database similar to [IAFIS](http://en.wikipedia.org/wiki/Integrated_Automated_Fingerprint_Identification_System) will certainly get created within a few years. Maybe even sooner. Police will finally have the tools needed to quickly identify suspects that have previously been processed through the criminal justice system for serious crimes DNA swabbing needs to be become a standard part of the booking procedure. The SCOTUS ruling specifically indicates DNA can be collected under the same guidelines as fingerprints. The quicker they get this in place the better. I wonder how long it will take for all the local police departments to include this in their booking procedures? It’s just one extra step that can be tied in with fingerprinting the suspect and taking the mug shot. > **[U.S. News: Latest Breaking Stories, Video, and Photos on American Politics,...](https://www.nbcnews.com/us-news?lite)** > > Get the latest news headlines and top stories from NBCNews.com. Find videos and news articles on the latest stories in the US. > [@](#): > > The five justices in the majority ruled that DNA sampling, after an arrest “for a serious offense” and when officers “bring the suspect to the station to be detained in custody,” does not violate the Fourth Amendment’s prohibition of unreasonable searches. > > Under those specifications, the court said, “taking and analyzing a cheek swab of the arrestee’s DNA is, like fingerprinting and photographing, a legitimate police booking procedure that is reasonable under the Fourth Amendment.” > > Scalia’s siding with the liberals reflects his growing concern over the past five years about privacy, said Tom Goldstein, the publisher of SCOTUSblog, who teaches at Harvard Law School and is a Supreme Court analyst for NBC News. ---
**Author:** ![StGermain](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stgermain/32/2868_2.png) [@StGermain](https://boards.straightdope.com/u/StGermain)\ **Post date:** [June 3, 2013, 6:58pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/7 "2013-06-03T18:58:04Z")
How will law enforcement ever deal with processing that many samples? Many jurisdictions are years behind on processing rape evidence, which I’d think would take precedence. Personally, I feel it would be okay upon conviction, but not simply being detained for questioning. StG ---
**Author:** ![Jas09](https://avatars.discourse-cdn.com/v4/letter/j/d07c76/32.png) [@Jas09](https://boards.straightdope.com/u/Jas09)\ **Post date:** [June 3, 2013, 7:39pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/8 "2013-06-03T19:39:14Z")
I rarely feel the need to say it, but today I will: nice work Justice Scalia. ---
**Author:** ![brickbacon](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@brickbacon](https://boards.straightdope.com/u/brickbacon)\ **Post date:** [June 3, 2013, 7:52pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/9 "2013-06-03T19:52:43Z")
Isn’t some of the issue that as we learn more and more about genetics, we can parse the data in ways that would be problematic? For example, you can often tel if there is a family match between two samples of DNA. Is it fair that when your brother gets arrested, part of your DNA becomes known to the government? ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 3, 2013, 7:56pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/10 "2013-06-03T19:56:08Z")
It’s worth noting that fingerprints exclude most suspects. Thats a huge help to the police during the early days of any investigation. The quicker they can find the right suspect the better. DNA will eventually take a similar role. Once a National database is established. Right now it takes weeks to get a suspects DNA tested. That process should speed up as technology improves and they build more facilities. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 3, 2013, 8:04pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/11 "2013-06-03T20:04:35Z")
Has any progress been made on establishing firm guidelines for a DNA match? Fingerprints require a certain number of matching ridge counts. If that threshold isn’t met then the evidence can’t be used in court. They need a similar threshold with DNA. It has to be a conservative level. You don’t want to convict someone on an inconclusive match. Some of the emerging DNA amplification methods in Europe worry me. If the DNA evidence is weak then don’t use it. There was a DNA guy from Europe that testified in the Casey Anthony case. I wasn’t impressed with his testimony (for the defense) at all. His lab seemed to be amplifying evidence from practically nothing. The FBI experts that testified were much more conservative in their testing. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [June 3, 2013, 8:07pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/12 "2013-06-03T20:07:28Z")
> [@LonghornDave](#): > > How can it possibly be argued that taking DNA is for identification purposes and not crime solving purposes? How can it be argued that fingerprints are for identification purposes and not crime solving purposes? I see DNA “fingerprinting” as being analogous to regular fingerprinting. You rub a piece of the person against a surface, analyze what remains on the surface. During future criminal activity, if any evidence is gathered that can be similarly analyzed, you can cross reference to the database. ---
**Author:** ![brickbacon](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@brickbacon](https://boards.straightdope.com/u/brickbacon)\ **Post date:** [June 3, 2013, 8:29pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/13 "2013-06-03T20:29:03Z")
> [@Cheesesteak](#): > > How can it be argued that fingerprints are for identification purposes and not crime solving purposes? Because it is one of a few immutable unique characteristics that can be used to differentiate one person for another. If you are arrested, how can I be sure you are you? How can know aside from taking fingerprints, iris scans, DNA, etc.? > [@Cheesesteak](#): > > I see DNA “fingerprinting” as being analogous to regular fingerprinting. It is analogous in many ways, BUT it can be used in many ways that would prove problematic. As I said before, DNA can be used for individual identification, but it also can be use for familial identification, genetic disease identification, genetic predisposition, etc. Your DNA is uniquely yours, but it is also partly share by plenty of others. Why should your arrest put others under suspicion? Your fingerprints don’t implicate your brother, but your DNA might. That’s one HUGE difference among a rapidly growing list of others. ---
**Author:** ![LonghornDave](https://avatars.discourse-cdn.com/v4/letter/l/a87d85/32.png) [@LonghornDave](https://boards.straightdope.com/u/LonghornDave)\ **Post date:** [June 3, 2013, 8:31pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/14 "2013-06-03T20:31:53Z")
> [@Cheesesteak](#): > > How can it be argued that fingerprints are for identification purposes and not crime solving purposes? > > I see DNA “fingerprinting” as being analogous to regular fingerprinting. You rub a piece of the person against a surface, analyze what remains on the surface. During future criminal activity, if any evidence is gathered that can be similarly analyzed, you can cross reference to the database. Is fingerprinting even a search under the fourth amendment? ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [June 3, 2013, 8:32pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/15 "2013-06-03T20:32:09Z")
Excluding suspects is DNA’s strength. It potentially can be a tremendous tool for police investigations. If someone matches then you occasionally have the dueling DNA experts for the prosecution and defense. Each side arguing their statistics over the significance of the match. Thats when other evidence and testimony helps the jury reach the right verdict. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [June 3, 2013, 8:50pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/16 "2013-06-03T20:50:11Z")
> [@brickbacon](#): > > Your fingerprints don’t implicate your brother, but your DNA might. That’s one HUGE difference among a rapidly growing list of others. Fair point, I hadn’t thought about it this way, and I’m not sure how I feel about it… ---
**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:** [June 3, 2013, 8:57pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/17 "2013-06-03T20:57:31Z")
I don’t see the family thing as being a big problem: The confidence threshold should be set high enough to exclude siblings, parents, or children (it’s not hard to do this, and still leave plenty of room for correct identifications). Revealing medical conditions might be more problematic, but only if revealed to the public or to insurance companies. Other than those two points, I don’t see any real difference between this and fingerprints. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [June 3, 2013, 9:13pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/18 "2013-06-03T21:13:45Z")
The danger is when police have DNA from a crime scene and search for a match in a database, without sufficient corroborating evidence that would convict without the DNA match. I believe that we don’t yet know enough about DNA comparisons to know the likelihood of a false match. To clarify, let’s take two different cases. A) We found a suspect due to other evidence (witnesses, placed at the scene, motive, etc.) and then found a DNA match with incriminating evidence (e.g., semen for a rape case). B) We found the DNA evidence and searched a database and came up with a match. Further evidence shows that the person might have been in the same city at the time of the crime – well, there’s no proof he _wasn’t_ there! For case A, the DNA match is damning. For case B, it’s a great way to whittle down the suspect list, but not incriminating because we don’t know how many false positives we might find when searching a database. This is a bit theoretical since I don’t think we have any databases, and it probably won’t be practical to have one in the short term. Currently, we rely on DNA samples themselves being available, and doing matches as with case A above. But at some point, it’ll be cheap enough to do the processing and save the data for every arrest. Hopefully we’ll also see a lot of good research to determine the probabilities for false positives among various populations. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [June 3, 2013, 9:15pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/19 "2013-06-03T21:15:13Z")
PS: regarding my point, there’s no difference between DNA and fingerprints. Both are subject to the same issues, though hopefully we have a better understanding of the statistics of false matches, and machine matches versus expert confirmation. ---
**Author:** ![Cheesesteak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cheesesteak/32/3694_2.png) [@Cheesesteak](https://boards.straightdope.com/u/Cheesesteak)\ **Post date:** [June 3, 2013, 9:25pm UTC](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046/20 "2013-06-03T21:25:16Z")
> [@Chronos](#): > > I don’t see the family thing as being a big problem: The confidence threshold should be set high enough to exclude siblings, parents, or children (it’s not hard to do this, and still leave plenty of room for correct identifications). I think the problem here is that the lab will know the DNA was from a family member, and how close a relation. Unless they’re legally required to give nothing but Match or No Match, the police will get the information. > [@](#): > > Revealing medical conditions might be more problematic, but only if revealed to the public or to insurance companies. I don’t think DNA matching works this way, it only identifies individual points of the DNA sequence. Like measuring a car by wheelbase, track, length, height, and angle of the windshield. You can probably exclusively identify a model of car with that data, but you won’t know what color it is, and you can’t draw the car with just that information. [Next page](https://boards.straightdope.com/t/dna-gathering-legal-once-arrested/660046.md?page=2)