At trial, a court may err in admitting evidence or excluding it. If the error does not affect a party’s substantial right, the error will be deemed harmless. See La. Code Evid. art. 103(A) (“Error may not be predicated upon a ruling which admits or excludes evidence unless a substantial right of the party is affected ....”).
When the error is one admitting evidence, the party alleging the error must make a timely objection; otherwise the error may not be reviewable on appeal. See La. Code Evid. art. 103(A)(1). In a jury trial, if the evidence is admissible as to one party or for one purpose, but inadmissible as to another party or for another purpose, the objecting party must request a limiting instruction; otherwise failure to give the limiting instruction cannot be raised on appeal. See La. Code Evid. art. 105. These rules are expressions of the basic principle governing preservation of error, discussed in this earlier post.
When evidence is not relevant to an issue raised in the pleadings, failure to object on grounds of irrelevance carries another hazard: expansion of the pleadings. Under La. Code Evid. art. 1154, when issues not raised in the pleadings are tried by the implied consent of the parties (i.e. by failure to object), they are treated as if they had been raised in the pleadings, and the court may allow amendment of the pleadings to conform to the evidence.
When the error is one excluding evidence, the party offering the evidence must make its substance known to the court. See La. Code Evid. art. 103(A)(2). The procedure for doing this is spelled out in La. Code Civ. P. art. 1636. Article 1636(A) requires the judge either to let the offering party make a statement setting forth the nature of the evidence or to make a complete record of it; the latter is often referred to as a proffer. Id. art. 1636(A). The proffer may be made in open court, on the record, and outside the jury’s presence; or it can be made by deposition. Id. art. 1636(B). If the court allows the offering party to make a proffer, it must allow other parties to make a counter-proffer. See id. art. 1636(D).
The reason for requiring a proffer was succinctly stated by the Louisiana Supreme Court in McLean v. Hunter, 495 So. 2d 1298, 1305 (La. 1986):
The very purpose of requiring a proffer is to preserve excluded testimony so that the testimony (whatever its nature) is available for appellate review. Without a proffer, appellate courts have no way of ascertaining the nature of the excluded testimony.
One other point on exclusion of evidence bears mentioning: the trial court must state the reason for its ruling that the evidence is inadmissible. Once the trial court does so, the ruling is “reviewable on appeal without the necessity of further formality.” See La. Code Civ. P. art. 1636(C). If the trial court fails to state the reason for its ruling, the party offering the evidence should object to the trial court’s failure to do so. Otherwise, an appellate court, drawing a negative implication from art. 1636(C), may conclude that the ruling is not reviewable.