Expert's opinion – is it always black & white ?Expert's opinion – is it always black & white ?(dactyloscopy, biological science )(dactyloscopy, biological science )

Highlights of Symposium Paper„Selected aspects of expert's opinion in fields of dactyloscopy and biological science”by J. Moszczyński, K. Krassowski & I.

Sołtyszewski

Bratislava, September 2007

Issue

Dactyloscopy and biological science (in particular DNA profiling) are common and popular areas of criminalistic expertise, where defintive – either positive or negative – results and identification

are both expected and demanded from an expert.

General public as well as reality of criminal proceedings recognizes dactyloscopic research and DNA profiling as hard

and unquestionable black-and-white evidence.

Reflecting on the present issue, we would like to raise two important points – is it really pure black & white, and what may

be the value of a non-definitive conlusions of an expert conducting the research

I. Dactyloscopy

When the problem of definitive opinion shows up ?

The problem does not exist in a case there is clean and well preserved trace.

The problem also does not exist in a case there is significantly deformed or decomposed, unreadable

trace.

The problem may exist in an intermediate situation – where there is a trace just on, or slightly below, the

edge of being usable for identification purposes.

Expert's dylema

Having the 'edge' trace available for your research, would you:

a.recognize the trace as not being usable for identification purposes at all

b. take the risk against the standards and your personal belief and issue a definitive opinion, as

requested

It does seem like loose-loose situation, doesn't it ?

The core of the problem – the B&W approach

The bottom line of the demonstrated problem is what we call black & white approach – as an expert you have the

common standard to qualify the given trace and you just need to be compliant with this standard.

Everything that falls within the standard is white, everything left outside is black. Life is simple and nice.

But – what do we really mean by 'standard' – is it always the same thing, is it universal, bullet-proof proven and

objective ?

Or – is there any real standard at all ?

The true meaning of 'standard'

In the real life-applied dactyloscopy it is all about the threshold set and methodology applied – and looks like they are both not

'standard' at all in different countries.

US, UK and Scandinavia – holistic expert's own standard approach prevails – a lot of freedom in assessing what is black

and what is white in a given case.

Continental EU – so called 'numerical' standard – minimal number of friction ridges established to qualify the given trace

positively for an identification – usually 12 friction ridges required.

And the million dollars question is:

Is there real, objective scientific base for both previously described approaches to the 'standard' enabling us to say

what is only black and what is only white in terms of usefulness for identification purposes ?

Or is it rather all based on the extensive experience of the experts that have subjectively agreed on something ( like

threshold value ) and also on other factors taken into account by the expert when performing the examination –

like overall readibility and shape of the trace, ability to apply alternative identification methods to it ( e.g.

poroscopy ).

Why not common sense approach ?The fact is that it is long-established tradition to issue only definitive

dactyloscopic opinions.

The fact is that probabilistic opinions in this field are associated with an unknown error margins, and are based on the subjective

assessment of an expert.

The fact is however too, that so-called dactyloscopic 'standards' used to qualify whether the trace is or is not useful for definitive opinion are

to large extent based on equally subjective agreements of experts.

From the general principle point of view it seems to be the same, subjective assessment of what is right and/or what is wrong.

So why not apply the common sense approach ?

The right answer requires the right question

Perhaps the problem lies in the questions that are being asked rather than with answers provided.

It is not about who is right and who is wrong, but what opinions are of use for criminal justice system.

Since we understand that black and white alternative is a false one when applied to qualification of dactyloscopic traces, we suggest that

it should be at least carefully considered whether and how probabilistic opinions should be introduced for the benefit of the

justice system.

According to the pool carried out among the interested parties in Poland ( experts, prosecutors, judges ), some 60% are in favour of

such an introcuction, while some 30% are opposing it.

II. Biological science: DNA profiling

DNA profiling – the other side of the story

While in case of dactyloscopy the presented problem is associated with too puristic and hardline approach

to probable opinions on the base of claimed standards, in DNA profiling we are faced with the

reverse problem – lack of agreed standards of provision of expert's opinions.

Diagnosis

The main source of the problem in this field is dispersed market of DNA labs – some are directly or indirectly controlled by the State ( Police labs, universities, research centres ), but some are just a

private entities.

It happens that opinions that are provided for the same, single case by the different labs, when

confronted, are either incompatible or impossible to evaluate and assess.

The key issue of compatibility

Regarding the biological research the key issue seems to be the compatibility of analyzed loci, in particular in the context of exchange of the data

between the DNA databases.

Consequently, the conclusion here is totally opposite to the dactyloscopy case – we believe more

standarization is necessary in order to improve usefulness of DNA profile opinions provided by the

experts on request of criminal justice system.

Closing remarks

Perhaps the closing conclusion of our paper is that some general reflection ( international cooperation

would be required ) is necessary regarding the meaning, understanding and interpretation of what

is called 'a standard' in the field of criminalistic expertize in general and in dactyloscopy and DNA

profiling in particular.