Widely accepted ideas can come crashing down in the face of new experimental evidence.
Scientifically accepted theories are constantly changing. The changes are generally small, noticed only by specialists in narrow fields. But over time, the sum of many little changes can bring about new understandings of how things work.
The history of science has taught us that widely accepted ideas can come crashing down in the face of new information. Our understanding of the world – all hypotheses, theories and natural laws – is a snapshot in time. A key tenet of science is that nothing is too sacred to be questioned.
We can never know how close we are to the real truth. Even some seemingly immutable theories cannot be directly tested.
The courts have always been concerned about “junk science.” Historically, witnesses have been allowed to give testimony that seemed to be based on science or scientific principles, when in fact it was not.
Judges are not, as a rule, scientific experts. Yet they are placed in the position of deciding which science makes it through the courtroom doors.
Through evidentiary hearings, judges assess whether the techniques, conclusions, and planned testimony used in a specific case are sufficiently valid to be admitted. Most importantly, they evaluate the underlying scientific principles on which the techniques rely.
The Daubert decision more directly encompassed the question of underlying principle. Daubert suggest that the court wanted sound scientific underpinnings for “scientific” evidence that came into court.
These questions reflect the experimentally testable predictions that can be generated by hypotheses in the scientific method. Understanding the scientific method allows for legal professionals to ask additional informed questions.
Daubert expands even further to address validity and reliability, as well as general acceptance.
No matter which standards are used, in the end, the justice system relies on a fact finder (judge or jury) to conclusively decide the facts of the case based on the interpretation of available evidence, which may or may not correlate to the truth. But the courts, in establishing criteria for the admissibility of scientific and technical evidence and testimony, try to admit reliable, informative information while excluding pseudo-scientific information.
Complications can occur when analysts are testifying: while proficiency tests are often performed to rate the ability of an analyst on a specific methodology, these exams may not test the analyst’s expertise in other areas that s/he may be called upon to address in a courtroom discussion, such as:
There is a significant difference between being able to physically set up and run a forensic test, and being able to explain what the test does, how it does it, and what the result actually means.
Calling the right expert to answer a particular question helps reduce the risk of a poorly informed analyst making a conclusion unwarranted by the science. For their part, attorneys and judges have a duty to understand what types of evidence and what kinds of statements each forensic practitioner is qualified to make.