Crime Scene Evidence Laying the Foundation for Crime Scene Evidence

In recent decades, significant advances in forensic technology and communications have revolutionized the art of collecting, sharing and using evidence to prosecute and convict accused criminals. These advances definitely make it easier for law enforcement (police and prosecutors) to put criminals away, but this not at the expense of the accused's constitutional rights to a fair trial. Therefore, courts have established different measures for ensuring that the forensic evidence that is used against a defendant is authentic and reliable. This paper will discuss the various safeguards in place and how law enforcement navigates through the process to maximize the benefit of the available forensic technology.

Generally speaking, on order for forensic evidence to be used against a defendant in court, the state must lay a proper foundation for that evidence. Specifically, this means the state must demonstrate that the evidence is authentic, reliable and relevant. The court (judge) in each individually case will determine whether the proper foundation has been laid, based on certain accepted standards established by statute or previous cases. Without the right foundation, the evidence cannot be used by the prosecution and the state will have a more difficult, or impossible, task of proving the defendant's guilt.

Authenticity

Authentic forensic evidence are items which are proven to be the same items collected from the crime scene, ranging from objects to bodily samples to photographs. Authentic items of forensic evidence typically do not photocopies of objects or replicas of items. Also it is the responsibility of the state to prove that the evidence is authentic. The Federal Rules of Evidence set forth the requirement for authentication in Rule 901 of the evidence code[footnoteRef:1]. Most of the time, the state only need introduce evidence through oral testimony of the chain...

[1: Federal Rule of Evidence 901 Requirement of Authentication or Identification-(a) General provision. -- The requirement of authentication or identification as a condition precedent to admissibility is satisfied by evidence sufficient to support a finding that the matter in question is what its proponent claims.]
Reliability

Reliability is also a key determinate in measuring the admissibility of evidence for which a proper foundation must also be established. Reliability of evidence equates to the likelihood that conclusions of certainty, free of doubt and speculation, can be drawn from the evidence. It is easiest to prove the reliability of a physical object. For instance, a weapon found at a crime scene will likely be admitted into evidence upon the testimony that the victim's wounds were consistent with the type of wounds made by that weapon and that the weapon was found at the crime scene.

Other types of evidence require more scientifically precise measurements to be accepted by the court, especially a scientific analysis of the type that is required for most forensic evidence (DNA, fingerprints etc.…). The Supreme Court has held that in order for scientific evidence to be reliable and therefore admissible, four criteria must be met:

1) The evidence must be based on a testable theory or technique;

2) The theory or technique must have been peer reviewed;

3) The particular testing technique used must have a known error rate and standards controlling the techniques operation; and

4) The underlying science must be generally accepted in the scientific community[footnoteRef:2]. [2: Daubert v. Merrell Dow Pharmaceuticals, Inc., 509…