Section 255.17 Adultery   
  A person is guilty of adultery when he engages in sexual  intercourse   with another person at a time when he has a living spouse, or the other  person   has a living spouse.   
 
  Adultery is a class B misdemeanor.
 
 
http://wings.buffalo.edu/law/bclc/we...ny3%28b%29.htm
Looks like the story has gone international:
http://www.associatedcontent.com/art...ery.html?cat=9
Suzanne Corona is Taken in Adultery
 
 	 		
 	
 	 		Published June 09, 2010 by:
 		
Mark  Whittington
Suzanne Corona, married mother of three, 
has  been caught having sex with a man on a picnic table in a public  park with a man twelve years her junior a short distance away from a  children's play area in  
 
 the small, New York town of Batavia.
Though  apparently most of their clothes were still on when they were caught  inflagranti delicto, Suzanne Corona and Justin Amend have been charged  with public lewdness. Moreover, Corona has been charged with adultery  according to a little known and little used New York state statute that  has been on the books for over the century.
"Section 255.17 of  the New York State penal law states: 'A person is guilty of adultery  when he engages in sexual intercourse with another person at a time he  has a living spouse, or the other person has a living spouse.'
"It  is now considered a Class B misdemeanour and is punishable by a £350  fine and 90 days in jail."
Despite the wording of the law, Justin  Amend has not also been charged with the same crime, which would tend  to be a problem of selective prosecution.
Most people, even those  who engage in it regularly, agree that adultery is morally wrong. It is  a violation of a promise made by most couples when they get married and  tends to lead to heart ache, legal trouble, and sometimes worse in  certain areas of the country where shooting one spouse's lover is still  customary. But most people would be shocked to find out that adultery is  technically a crime in ten states.
In most cases, marital  infidelity has been considered a private matter between the husband,  wife, and the correspondent lover. This was true even when the husband  was President Bill Clinton, the wife Hillary Rodham Clinton, and the  lover Monica Lewinski. Mind, in that case it was really not a private  matter, due to the high profile of the people involved and how the  dangerous liaisons let to perjury, obstruction of justice, and the  second impeachment of a US President in history.
But, as Suzanne Corona's husband is standing by her and appears to have  forgiven her for her indiscretion, one cannot see how the matter should  be the subjection of a legal prosecution. One suspects that the local  
 
 district attorney will drop the adultery  charge and the lewd conduct will be pled down. The shame Suzanne Corona  is evidently feeling is greater punishment than anything that the State  of New York can inflict on her.
Source: Hand-in-hand with her  husband, the mother accused of adultery after  picnic passion with lover  in a U.S. public park, Daily Mail, JUne 9th, 2010