N.Y. CPL Law § 60.20

§ 60.20 Rules of evidence; testimonial capacity; evidence given by\n children.\n 1. Any person may be a witness in a criminal proceeding unless the\ncourt finds that, by reason of infancy or mental disease or defect, he\ndoes not possess sufficient intelligence or capacity to justify the\nreception of his evidence.\n 2. Every witness more than nine years old may testify only under oath\nunless the court is satisfied that such witness cannot, as a result of\nmental disease or defect, understand the nature of an oath. A witness\nless than nine years old may not testify under oath unless the court is\nsatisfied that he or she understands the nature of an oath. If under\neither of the above provisions, a witness is deemed to be ineligible to\ntestify under oath, the witness may nevertheless be permitted to give\nunsworn evidence if the court is satisfied that the witness possesses\nsufficient intelligence and capacity to justify the reception thereof. A\nwitness understands the nature of an oath if he or she appreciates the\ndifference between truth and falsehood, the necessity for telling the\ntruth, and the fact that a witness who testifies falsely may be\npunished.\n 3. A defendant may not be convicted of an offense solely upon unsworn\nevidence given pursuant to subdivision two.\n