What's The US Law on Exhumations?

Recently, it was learned that Robert Kennedy had the body of his ex-wife exhumed and moved to another part of the cemetery.
As I understand it, exhumations are frowned upon by law-the only grounds for allowing it are:
-crime investigations (seeing if the deceased was a murder victim)
-moving the body because of construction (like a dam flooding the area)
So, suppose you wanted to move grandpa to a nicer neighborhood-do you have to get a judge’s permission/court order) to dig up the deceased?

AFAIK, you can exhume and move a body if your family owns the plot.

The court order is only needed for a crime investigation if the family doesn’t agree to it. It may also be required when the ownership of the plot is in doubt.