I hve joint custody of my 8 yr old daughter... father has phys placement. what are the laws that allow a child to change custody

There is no magic age when children get to decide where to live. The best interest of the child is the standard.

The law regarding a child's 'right'* to choose is a matter for each State and jurisdiction. The judge in most States, not the child, makes the decision based on the best interest of the child. Although not a standard by any means, many States have begun to give 'consideration' to a child's declaration of custodial preference when the child reaches the age of twelve or thirteen, sometimes fourteen. There are even cases when children of age 9 are allowed to testify.

The judge is normally given almost unlimited latitude in whether or not she or he listens to a child and how much weight to give to the child's wishes. In short, there is no specific "age" but the younger the child the less likely for a judge to give the stated preference much weight.

Good luck to you.

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That's an extremely difficult question to answer.

In New York, the rule on custodial modifications (changes) is that there has to be a "change in circumstances" and that the modification is in the best interests of the child.

However, having no clue about how it is you ended up out of custody stops the analysis here.

Typically, dads get custody if the mom is so far out of it that there is no way to leave the child with mom. If this happened to you, then the fight will be much harder. Another way dads get custody is if they have access to the forensic evaluator and can manipulate the evaluation. Again, any damage done to your reputation in litigation will increase your burden of changing custody back to you.

But no matter what you do, never try family court in New York without competent counsel who is well versed in family law.