In most states, no. However, in some states they are allowed under certain circumstances.
It's typically not within the trial judge's discretion when to and not to admit this evidence. Most states' appellate/supreme courts have set out rules in case law for when polygraph is admissible.
For example, in several states, a polygraph is admissible in a criminal case when it is first introduced by the defendant, but the state may not be the first to introduce it. However, if the defendant introduces a polygraph test, the state may rebut that evidence with a conflicting exam.
Not in the US
your dog
Yes, if it doesn't violate the rules of evidence.
A judge has final say on what is or is not admissable in their court. The only recourse if the evidence was refused is to file for an appeal and have the appeals court see if his/her refusal of the evidence was justified. If they find in favor of the judge, you're out of luck. If on the other hand the appeals court decides the evidence should be admissable, the case will most likely be retried with the new evidence presented.
Although the use of polygraph results as evidence in court is regularly challenged - it IS a useful tool and is used in the preliminary stage of many criminal investigations.
No.
It will depend on the evidence, but probably yes. In most cases the report is not the entire recollection of the police officer.
Yes, it MAY be allowed. The "age of reason" for children in most states is usually set at, or about, 7 years of age.
No, it does not have to be court ordered to be applicable in court.
no
Yes, if the evidence has already been ruled admissable in court, it can be used again. The more evidence that proves the point, the better.
If it used to quote a necessary piece of overheard dialogue, or to quote what a defendant or other principal in the case said, yes. To simply testify and/or use it in everyday court conversation and answers to other questions, no, it is not.