Exchanging Expert & Non-Expert Information Prior to Trial:
During a trial, testimony from laymen and expert witnesses are a crucial tool in proving your case. For this reason, it is important to decide before discovery is complete what all potential witnesses have to say, and whether you will need an expert witness to prove any of the elements of your case.
To avoid a non-party witness being precluded from testifying at trial, you must ensure that you exchange non-party witness information well in advance. The Second Department has held that non-party occurrence witnesses and witnesses testifying on the issue of notice must be exchanged. Although there is a dearth of case law specifically addressing the issue of non-expert damages only witnesses, under the liberal rules of disclosure, good practice requires disclosure of these witnesses as well. 
In preparing your trial, if you expect to call an expert to testify, make sure you have exchanged that expert’s information pursuant to CPLR 3101(d) and 22 NYCRR 202.17. 22 NYCRR 202.17 requires the exchange of any records and reports prepared or created by your expert prior to the time of trial. CPLR 3101(d) requires you to identify the expert’s name, their qualifications, and the substance of the facts and opinions you expect them to testify about. However, there is a notable exception to this rule: Treating physicians need not be disclosed pursuant to CPLR 3101(d) so long as that physician’s medical records and reports are exchanged and an authorization is provided to the defense. Of note, The Second Department has permitted a treating doctor to testify as to their opinion on causation, even if not explicitly noted within the four corners of his/her medical records. With regard to a treating medical expert, it is good practice to provide the defense with updated treatment records along with an expert exchange similar in scope to that contained in a CPLR 3101(d) exchange. When done well in advance of trial, this will prevent claims of prejudice by the defense seeking to limit the expert’s testimony.
 Zayas v. Morales, 45 A.D.2d 610, 612, 360 N.Y.S.2d 279, 281 (2d Dep’t., 1974)
 See generally, Id. at 613 (“The purpose of litigation is to achieve a just result and not to spring a surprise on one’s adversary. That purpose can only be hindered—not served—by failing to make proper disclosure of matters material and necessary to the prosecution or defense of an action.”); see also CPLR 3101.
 22 NYCRR 202.17 (“no party shall be permitted to offer any evidence of injuries or conditions not set forth or put in issue in the respective medical reports previously exchanged, nor will the court hear the testimony of any treating or examining medical providers whose medical reports have not been served”); Frangello v. Namm, 157 A.D.2d 649, 649, 549 N.Y.S.2d 748, 749 (2d Dep’t, 1990)(22 NYCRR 202.17(h) requires the medical report of any testifying medical expert be served upon the opposing party prior to trial).
 Logan v. Roman, 58 A.D.3d 810, 810, 872 N.Y.S.2d 491, 492 (2d Dep’t, 2009)(“Since Dr. Walsh was the plaintiff’s treating physician, he should have been permitted to testify at trial notwithstanding any failure or deficiency in providing disclosure pursuant to CPLR 3101(d)(1)(i), as that provision does not apply to treating physicians”); Overeem v. Neuhoff, 254 A.D.2d 398, 400, 679 N.Y.S.2d 74, 76 (2d Dep’t, 1998)
 Kowalsky v. Cty. of Suffolk, 139 A.D.3d 903, 905, 34 N.Y.S.3d 75, 78 (2d Dep’t, 2016)(“a plaintiff’s treating physician ‘could testify to the cause of the injuries even if he [or she] had expressed no opinion regarding causation in his [or her] previously exchanged medical report’”); Logan v. Roman, 58 A.D.3d 810, 811, 872 N.Y.S.2d 491, 492 (2d Dep’t, 2009);