Parties rely on expert testimony not only at trial but also when making and opposing summary judgment motions. Accordingly, it is important to know when a party needs to disclose the identity of his expert witness.

In New York, CPLR 3101(d)(1) requires parties to identify each person whom they expect to call as an expert witness at trial. However, this section does not indicate a deadline by which expert disclosure must be made.

The Appellate Division, Second Department recently decided, in Vlahakis v. Belcom Development LLC, that the defendant was not allowed to include his expert’s affidavit in his opposition to the plaintiff’s summary judgment motion because the expert’s identity had not been revealed until after the note of issue and certificate of readiness had been filed. Further, the defendant failed to show good cause for the delay. Accordingly, the court considered the opposition without the expert’s affidavit, which was insuffcient to overcome the plaintiff’s motion.

Thanks to Georgia Stagias for her contribution to this post.