There are many ethical rules that lawyers are obligated to follow. The ethics class is usual a semester in most NY law schools. Hard to teach you everything in the 4000 characters that these answers allos.
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Lawyers do have ethical standards governing our conduct toward clients, the Courts and even third parties who we do not represent. I agree with the other attorney who provided you with a link to New York's Rules of Professional Conduct. You will find Rule 3.4 entitled: "Fairness to Opposing Party and Counsel" enlightening. (see p.19 of the Rules)