DNA law change

[Pixie]

Yep, DNA profiling saved his arse nicely. From a contemporary point of view if someone was to go through the same process now they would be exonerated immediately rather than being imprisoned for years.

Or alternatively,a crooked cop (Hypothetical,of course.We know they don't exist in NZ) could obtain a couple of blond hairs from a victim's brush,and plant them on the accused's yacht

[scumdog]

Or alternatively,a crooked cop (Hypothetical,of course.We know they don't exist in NZ) could obtain a couple of blond hairs from a victim's brush,and plant them on the accused's yacht

Like they could also have got items handled by the suspect and planted them there too..

Or planted said hairbrush there too...

Or..

[Pixie]

Rather more so, in fact. Fingerprints are unique (or at any rate no one's found a duplicate in over 100 years).

But DNA ID , as used for law enforcement purposes, is far from unique. The degree of exactitude does not extend down to a specific unique person. The results will only show a probability of match " The DNA from this person is a million times more likely to be from the same person who left the crime artefact as a random person" . In other words, there are , statistically, four other people in the country who it could equally likely be from. And the odds go way up if there are related people.

But it is never put that way tot the jury . it is always "Scientific DNA evidence proves that the DNA came form the defendant". It "proves" no such thing (proves nothing in fact) but that's how it's always presented. And juries, being largely composed of stupid people swallow it. "It's scientific, izzn it? Must be true".

Fingerprints are unique,but the protocols for comparison only examine less than 10 points of equivalence.Whereas DNA profiles are compared over thousands of points.

WIKI: The few tests of validity of forensic fingerprinting have not been supportive of the method:

Despite the absence of objective standards, scientific validation, and adequate statistical studies, a natural question to ask is how well fingerprint examiners actually perform. Proficiency tests do not validate a procedure per se, but they can provide some insight into error rates. In 1995, the Collaborative Testing Service (CTS) administered a proficiency test that, for the first time, was “designed, assembled, and reviewed” by the International Association for Identification (IAI).The results were disappointing. Four suspect cards with prints of all ten fingers were provided together with seven latents. Of 156 people taking the test, only 68 (44%) correctly classified all seven latents.Overall, the tests contained a total of 48 incorrect identifications. David Grieve, the editor of the Journal of Forensic Identification, describes the reaction of the forensic community to the results of the CTS test as ranging from “shock to disbelief,” and added:

Errors of this magnitude within a discipline singularly admired and respected for its touted absolute certainty as an identification process have produced chilling and mind- numbing realities. Thirty-four participants, an incredible 22% of those involved, substituted presumed but false certainty for truth. By any measure, this represents a profile of practice that is unacceptable and thus demands positive action by the entire community.

What is striking about these comments is that they do not come from a critic of the fingerprint community, but from the editor of one of its premier publications.

DNA: In the early days of the use of genetic fingerprinting as criminal evidence, juries were often swayed by spurious statistical arguments by defense lawyers along these lines: given a match that had a 1 in 5 million probability of occurring by chance, the lawyer would argue that this meant that in a country of say 60 million people there were 12 people who would also match the profile. This was then translated to a 1 in 12 chance of the suspect being the guilty one. This argument is not sound unless the suspect was drawn at random from the population of the country. In fact, a jury should consider how likely it is that an individual matching the genetic profile would also have been a suspect in the case for other reasons. Another spurious statistical argument is based on the false assumption that a 1 in 5 million probability of a match automatically translates into a 1 in 5 million probability of guilt and is known as the prosecutor's fallacy.

When using RFLP, the theoretical risk of a coincidental match is 1 in 100 billion (100,000,000,000), although the risk is actually 1 in 1000 because monozygotic twins are 0.2% of the human population. Moreover, the rate of laboratory error is almost certainly higher than thispractical , and often actual laboratory procedures do not reflect the theory under which the coincidence probabilities were computed. For example, the coincidence probabilities may be calculated based on the probabilities that markers in two samples have bands in precisely the same location, but a laboratory worker may conclude that similar—but not precisely identical—band patterns result from identical genetic samples with some imperfection in the agarose gel. However, in this case, the laboratory worker increases the coincidence risk by expanding the criteria for declaring a match. Recent studies have quoted relatively high error rates which may be cause for concern[5]. In the early days of genetic fingerprinting, the necessary population data to accurately compute a match probability was sometimes unavailable. Between 1992 and 1996, arbitrary low ceilings were controversially put on match probabilities used in RFLP analysis rather than the higher theoretically computed ones [6]. Today, RFLP has become widely disused due to the advent of more discriminating, sensitive and easier technologies.

STRs do not suffer from such subjectivity and provide similar power of discrimination (1 in 10^13 for unrelated individuals if using a full SGM+ profile) It should be noted that figures of this magnitude are not considered to be statistically supportable by scientists in the UK, for unrelated individuals with full matching DNA profiles a match probability of 1 in a billion (one thousand million) is considered statistically supportable (Since 1998 the DNA profiling system supported by The National DNA Database in the UK is the SGM+ DNA profiling system which includes 10 STR regions and a sex indicating test. However, with any DNA technique, the cautious juror should not convict on genetic fingerprint evidence alone if other factors raise doubt. Contamination with other evidence (secondary transfer) is a key source of incorrect DNA profiles and raising doubts as to whether a sample has been adulterated is a favorite defense technique. More rarely, Chimerism is one such instance where the lack of a genetic match may unfairly exclude a suspect

Chimerism is a state where an individual has tissue material from another organism within his body - an unborn sibling,or a sheep,for example

[Cynos]

Napoleon once said - never attribute to malice what can be adequately explained by incompetence.

And that's what I fear in this. If the Police start sampling everyone arrested on charges imprisonable etc. etc., the potential for cross-contamination and/or other errors increases dramatically.

I don't think the Police would use their power evilly, but I have no problem believing that they are human, and overworked and under-resourced.

[Ixion]

She could have got an 18+ card.

Not accepted. Drivers licence, passport, firearms licence, police ID card, armed services ID card. That's it.

And as someone mentioned, not just the old people. What about a 16 year old who hasn't a drivers licence or passport?

[spudchucka]

Not accepted. Drivers licence, passport, firearms licence, police ID card, armed services ID card. That's it.

And as someone mentioned, not just the old people. What about a 16 year old who hasn't a drivers licence or passport?

Its bank policy, nothing to do with any govt department.

[spudchucka]

Fingerprints are unique,but the protocols for comparison only examine less than 10 points of equivalence.

You're out of date I'm afraid. Google "ridgeology".

[Ixion]

Its bank policy, nothing to do with any govt department.

They claim it is a requirement of the Reserve Bank. Which is a government department.

[Ixion]

I see even Granny Harold has an editorial expressing concerns about the proposal. Which speaks much. Granny also raises the significant point, that DNA is not just for identification. It can tell much about the person concerned. At an extreme, it could identify people having some "inferior" genetic characteristic. And there are people in our society who, given that information being readily available would call for laws to (at least) prevent such folk breeding (purely for their own good, of course - it always is) . It is only the present difficulty of identifying the target that stops them. They might find it hard to obtain traction as regards public acceptance, though I'm would not be too confident of that. New Zealand is not a society very accepting of difference or of the disabled.

Insurance companies are another that would find that information very useful. They could use it to identify people who might have a genetic propoensity to conditions that could be expensive for them. And armed with the information , refuse insurance to such unfortunates (who might well be unware themselves of the fact).

Once the Police have this sort of information it is quite certain that others will soon have it too.

[spudchucka]

You don't need a DNA sample to figure out who is from the shallow end of the gene pool.

You really are displaying quite spectacular levels of paranoia.

[jrandom]

You really are displaying quite spectacular levels of paranoia.

You, the reasonable and hard-working copper who just wants to get his job done, think it's paranoia.

Unfortunately, it's not you we have to worry about.

Why is it that every time laws are introduced anywhere that deprive citizens of privacy and/or liberty, people scoff and either say that:

(a) if you're doing nothing wrong, you have nothing to fear, or

(b) you're paranoid, don't worry, nobody would ever dream of using these new powers unreasonably or for purposes they weren't intended for.

How about those 'anti-terrorism surveillance' laws in the UK that are being used to catch people putting their rubbish out on the wrong day?

The intelligent citizen, unfortunately, must consider the worst-case scenario and assume that laws will be abused by those given the power to wield them, simply because human nature inevitably ensures that that will happen.

History gives the lie to your accusations of 'paranoia'.

[Clockwork]

Or alternatively,a crooked cop (Hypothetical,of course.We know they don't exist in NZ) could obtain a couple of blond hairs from a victim's brush,and plant them on the accused's yacht

.... also, it would be harder to plant fingerprints at a crimescene than it would to plant DNA

[Patrick]

Or alternatively,a crooked cop (Hypothetical,of course.We know they don't exist in NZ) could obtain a couple of blond hairs from a victim's brush,and plant them on the accused's yacht

But why? Then the real killer would still be out there.... kinda misses the reasons for catching the killer really....

[Max Preload]

But why? Then the real killer would still be out there.... kinda misses the reasons for catching the killer really....

Well, it certainly helps them cover up their incompetence in ignoring expert eye-witness statements nicely!

"No, no - it wasn't a ketch - it was two sloops tied together! We know all about those, ah, boaty things!"

[Patrick]

Well, it certainly helps them cover up their incompetence in ignoring expert eye-witness statements nicely!

"No, no - it wasn't a ketch - it was two sloops tied together! We know all about those, ah, boaty things!"

Ah... so the sloop did it...

Kinda ignores the cleaning with bleach (which destroys blood stains apparently) the hard to find/see hairs that were "missed" in the "cleanup" and a whole raft of other things.... Like all 12 members of a jury being convinced....

Oops... "raft" of things... it wasn't a sloop or a ketch... it was a raft...?

Silly I know... but its one of those days....