No. According to amer acad peditrics practice guidelines for adhd, a doctor must recommend stimulant medication. The parents have ultimate say in what/how their child is treated. Having said that, untreated adhd is such a devastating, chronically pervasive condition that not treating it amounts to sentencing a child to an inferior life, increasing risk for drugs, motor accidents, financial problems.
Should refer. It is not illegal for a physician to decide they do not want to treat ADHD with medication, but they should refer you to a physician who can provide appropriate services. If you are asking about a parental decision, that is up to the parent.
No. It is not illegal, but it is wrong!