The Rules of Admissibility: Competence
Competence doesn’t mean the same thing in the law as it does in everyday life. It doesn’t have anything to do with the ability to do something. It is a collection of rules and constraints that evidence must pass muster with in order to be admissible.
• Prejudice—Prejudicial evidence may be highly relevant but also has the effect of being viewed negatively by the jury. It can impugn the reputation or the accused or turn the jury against him. Consider some examples. In many jurisdictions, color photographs of an autopsy of the victim of a violent homicide may not be admissible because their graphic nature may cause the jury to focus on the gore and blood they depict, at the expense of their value as evidence. They may view the defendant as being guilty because of the photographs of the victim. Unless the sponsoring pathologist can make a case that these color photo graphs are necessary to illustrate certain probative facts about the killing, these photos may not be admissible. In many cases, black and white photographs are used instead because they do not have the same negative impact of color photos. Prejudice is also one of the major reasons why a defendant’s prior criminal record is not admissible evidence of guilt in a trial on a similar charge because the jury may feel that, because he or she committed similar crimes before, means that he or she did it again. Thus, the jury may convict the defendant because of the previous crimes and not because of the facts of the case at issue.
• Time wasting—Although attorneys are generally given wide latitude to prosecute and defend in criminal cases, judges will generally not tolerate evidence that wastes time because it is unnecessarily cumulative or repetitive or lacks relevance. This has the effect of distracting and perhaps even confusing the jury. An example of this is illustrated by a situation where a large number of people witness the same event and the prosecutor wants to bring all of them in to testify as to what they saw. In such cases, the judge may limit the testimony to one or two representative witnesses.
• Unreliable—This is one of the criteria that govern the admissibility of certain scientific (and perhaps pseudoscientific) evidence. Evidence must be reliable if the jury is to be able to weigh it properly in reaching a decision about guilt or innocence. This is also the reason that much eyewitness testimony is discredited in court. Research has shown that, when witnesses experience a startling or surprise event, their recollections can differ widely from one person to the next. Each person reacts to such events differently and their reactions will bias their perceptions about what they experienced. Another form of unreliable evidence is hearsay. Hearsay is defined as a statement, made by someone outside of a courtroom and not under oath, and which is now being used inside court to prove what it asserts. An example of hearsay would be if John Smith witnessed a crime committed by Joe Smash and Smith tells George Ruth what he saw and then Ruth offers to testify in court what Smith told him about the crime. If the testimony by Ruth is being used to prove that Smash committed the crime, this would be hearsay. Some types of hearsay may be considered unreliable because they are difficult or impossible to effectively cross-examine someone who did not witness something but is only repeating something that he heard. There are numerous exceptions to the hearsay rule. For example, suppose that a forensic scientist analyzed some plant material and concluded that it was marihuana and wrote a report that communicated these findings. At trial, the prosecutor wishes to introduce the report as evidence to prove that the plant material was marihuana. The report may be admissible under certain circumstances even if the scientist is not present, even though it would be technically considered to be hearsay. The difficulty of cross-examining a laboratory report can be appreciated, but it may be admissible if properly attested and agreed to by both sides. The laboratory report may also be important when a long period of time has elapsed between the time the scientist analyzed the evidence and wrote the report, and the time of the trial. The scientist may not remember doing the analysis in this specific case and the laboratory report then stands as the most reliable evidence of what was done to the evidence. This will be discussed in the section below on laboratory reports.
• Improper procedures—Courts generally do not allow surprise witnesses to testify without giving notice to the other side. Evidence is also generally inadmissible if it is offered out of turn or after the proponent has already rested his case. Attorneys are not allowed to present testimony during an opening or closing argument. These prohibitions against improper evidence are all in place to protect the jury as well as the rights of the accused.
• Existence of privileges—In the legal context, a privilege is a protection given to someone to protect that person from having to offer testimony against another person. There are certain privileges that exist in many locales that have been created by legislation. These include the attorney–client, doctor–patient, cleric–penitent, and marital privileges. All of these in some way are designed to protect sensitive or intimate or otherwise special communications. The attorney client privilege, for example, protects communications between an attorney and the client by allowing an attorney to refuse to testify to such communications. Likewise, a priest is protected from testifying about the contents of confessions made by a member of the congregation. There are two marital privileges: one that protects one partner in a marriage from testifying against the other, and a privilege that permits one partner to silence the other partner who wishes to testify. There are, of course, many exceptions to the privileges mentioned here. In many states, privileges do not exist in the absence of legislation that explicitly permits them. Even in these cases, however, it would be impractical to prosecute someone for exercising a privilege such as a minister who refuses to testify about what he heard in a confession.
•Constitutional constraints—Certain provisions of the Constitution, discussed earlier provide for the exclusion of evidence and/or testimony where violations have occurred. These include evidence seized in violation of the Fourth Amend ment and testimony of self-incrimination covered by the Fifth Amendment. In summary, evidence will be admissible in court only if it is both relevant and competent. This applies to all evidence in a criminal case. Next, we will turn to the question specifically of the admissibility of scientific or expert evidence. We will see that because of its technical nature; it is treated somewhat differently than nonscientific evidence.
