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Law 101: Legal Guide for the Forensic Expert

The Scientific Method


Infographic demonstrating the scientific method. Caption says "Scientific Method, Purpose, Research, Hypothesis, Experiment, Analysis, and Conclusion'
National Institute of Justice (NIJ) (see reuse policy).

Scientific Method. The principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation. The scientific method generally involves observing a phenomenon, formulating a hypothesis concerning the phenomenon, experimenting to determine whether the hypothesis is true or false, and a conclusion that validates or modifies the hypothesis.

The witness can review a scientific or medical report or a testing analysis. The witness can also help the attorney determine and identify what results could be recreated by a retest of the opposing experts' analysis.

An expert can educate the attorney on the specific scientific discipline's basic elements. The attorney may also need to be educated regarding the method(s) and testing procedure(s) used in the case. An expert may be necessary to explain why the specific method, procedures, equipment, etc., were chosen over other available ones (including a specific lab protocol, a standard operating procedure, etc.).

The expert may recommend additional literature or scientific publications related to the discipline or testing procedure. He or she should include relevant technical literature and "learned treatises" that may be used by the other party's experts.

A witness can also help prepare the attorney for case theories, discovery, deposition, direct examination and cross-examination by providing a list of predicate questions related to the discipline. 

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