Motion Requirements

On motion of any party who has engaged in a timely exchange of expert witness information, the court may grant leave to:

1. augment that party’s expert witness list and declaration by adding the name and address of any expert witness whom that party has subsequently retained; and/or
2. amend that party’s expert witness declaration with respect to the general substance of the testimony that an expert previously designated is expected to give.

(Code Civ. Proc., Sec. 2034.610(a).)

This motion shall be made a sufficient time in advance to permit the deposition of any expert to whom the motion relates to be taken before the discovery cut-off, unless exceptional circumstances exist. (Code Civ. Proc., Sec. 2034.610,(b).) The motion shall be accompanied by a meet and confer declaration. (Code Civ. Proc., Sec. 2034.610(c).)

Court's Considerations

The court shall grant leave to augment or amend an expert witness list only if all of the following conditions are satisfied:

1. The court has taken into account the extent to which the opposing party has relied on the list of expert witnesses.
2. The court has determined that any party opposing the motion will not be prejudiced in maintaining that party’s action or defense on the merits.
3. The court has determined either of the following:
   1. The moving party would not in the exercise of reasonable diligence have determined to call that expert witness or have decided to offer the different or additional testimony of that expert witness.
   2. The moving party failed to determine to call that expert witness, or to offer the different or additional testimony of that expert witness as a result of mistake, inadvertence, surprise, or excusable neglect, and the moving party has done both of the following:
   1. Sought leave to augment or amend promptly after deciding to call the expert witness or to offer the different or additional testimony.
   2. Promptly thereafter served a copy of the proposed expert witness information concerning the expert or the testimony described in Section 2034.260 on all other parties who have appeared in the action.
4. Leave to augment or amend is conditioned on the moving party making the expert available immediately for a deposition under Article 3 (commencing with Section 2034.410), and on any other terms as may be just, including, but not limited to, leave to any party opposing the motion to designate additional expert witnesses or to elicit additional opinions from those previously designated, a continuance of the trial for a reasonable period of time, and the awarding of costs and litigation expenses to any party opposing the motion.

(Code of Civ. Proc. Sec. 2034.620.)

Judicial Interpretation of Section 2034

The spirit of Code of Civil Procedure section 2034, though apparently not the letter of subdivision (j) itself, implies that a party who wishes to call at trial an expert who was not designated when expert witness information was exchanged and who is intended to take the place of a previously designated but now unavailable expert, must make a motion under subdivision (k) to augment that party's expert witness list to include the new expert. (Richaud v. Jennings (1993) 16 Cal.App.4th 81, 90-91.) The party cannot do nothing and then insist that the replacement expert can be called at trial on the ground that the party's failure to list the replacement expert when expert witness information was exchanged was not "unreasonable." (Id.) Nor can the party comply with the statute by unilaterally, without leave of court and at any time the party chooses, simply serving a so-called "supplemental" expert witness designation listing the new replacement expert. (Id.)

Other Circumstances for Augmentation

Augmentation of the expert witness designation has been allowed where the expert passed away before trial (see Richaud v. Jennings (1993) 16 Cal.App.4th 81, 89), as well as where the expert’s conclusions and deposition testimony were found to be unexpectedly detrimental to the party offering the expert (see Dickison v. Howen (1990) 220 Cal.App.3d 1471, 1478.)