“We reside in New York State. My fiance’s ex filed custody papers with the courts stating that he abused their daughter. She later left a message on our home answering machine admitting that she lied. She stated that had he not told her psychiatrist that he was going to seek custody of their daughter, she would not have submitted a petition for custody. Will he be able to use this tape in court to show the judge that she lied?”
The general rule is that a tape recording made without the consent of the recorded party is not admissible. That is why everybody seems to know that you are supposed to tell people when you are taping a conversation with them.
However, the laws of many states recognize that if someone is leaving an answering machine message, then they know that they are being recorded, and so they are giving you permission to record them. In those states, an answering machine message may be introduced in court as evidence.
You will need to consult with an attorney in New York to determine whether New York is one of those states. You can also try asking the clerk of courts at the court house, but an attorney is probably your best bet.