Q: What is the legal definition of adultery? And or what would a court consider adultery?

A: I think you are probably more interested in the tort, "alienation of affection." My understanding is that only Mississippi and North Carolina still recognize this tort, although North Carolina has up to 200 cases a year based on it.

For the history of the tort, see http://caselaw.findlaw.com/mo-supreme-court/1352874.html

"An alienation of affections claim arises when a defendant intentionally interferes with a marriage, straining relations between the spouses."

"Alienation of affections claims typically fell into one of two classes: (1) suits against a man or woman with romantic designs on a spouse and (2) claims brought against meddling in-laws. A higher burden of proof applied to alienation of affections suits against the latter class of defendants; a presumption existed that relatives acted with proper motives."

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1129642

Note that there is no single legal definition of adultery. You have the federal government and 50 states and there might be differences (some minor) in each state. You also have the military which has its own code for adultery.

Finally: "The Supreme Court has not yet extended the “right to privacy” to include the right to commit adultery. However, the Sixth and Ninth Circuit Court of Appeals have extended the “right to privacy” to include this act."

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2446046

Thus, there is an argument that the government may not punish such an act to be considered. A court may, or may not, agree.

www.lehmanlawgroup.com

A: I think you are probably more interested in the tort, "alienation of affection." My understanding is that only Mississippi and North Carolina still recognize this tort, although North Carolina has up to 200 cases a year based on it.

For the history of the tort, see http://caselaw.findlaw.com/mo-supreme-court/1352874.html

"An alienation of affections claim arises when a defendant intentionally interferes with a marriage, straining relations between the spouses."

"Alienation of affections claims typically fell into one of two classes: (1) suits against a man or woman with romantic designs on a spouse and (2) claims brought against meddling in-laws. A higher burden of proof applied to alienation of affections suits against the latter class of defendants; a presumption existed that relatives acted with proper motives."

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1129642

Note that there is no single legal definition of adultery. You have the federal government and 50 states and there might be differences (some minor) in each state. You also have the military which has its own code for adultery.

Finally: "The Supreme Court has not yet extended the “right to privacy” to include the right to commit adultery. However, the Sixth and Ninth Circuit Court of Appeals have extended the “right to privacy” to include this act."

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2446046

Thus, there is an argument that the government may not punish such an act to be considered. A court may, or may not, agree.

www.lehmanlawgroup.com