Legal Question in Traffic Law in New York

It's not illegal, but their testimony would be hearsay unless they actually observed the violation. Sometimes two officers witness a violation, and either one can testify regardless of whether they actually wrote the ticket.

It depends. Was this for a pre trial conference or for a trial.

We had a problem with one court where a police officer was offering plea deals for state troopers, which is not legal in New York. As Mr. Kurtzrock mentioned, an officer may not be able to testify at trial about what someone else saw. If the second officer also saw the offense, the first officer may not need to appear.