In United State of America, all the states have a Grand Parent Visiting law that allows the grand parent to seek courts order to maintain contact with their grand children. In respect of grandparents visitation right there is no uniform law, so different States have their own rulings. Some states are liberal and some are not. More over the Supreme Court of America has recognized that right of the parent in custody, care and control of the child is supreme and grandparents visitation right is an unconstitutional right.
 
In case one of the parents passes away, the guardianship of the grand child goes to the surviving parent even if he/she has not maintained any contact with the child since long. In case both the parents are dead and have left the will, the legal guardianship of the child goes to the nominated legal guardian. Grandparents visitation right leaves them on the mercy of the legal guardian and they have to seek courts permission in their respective states.
 
Even, in case there is no will left behind and there is no legal guardian, the grandparent still have to secure court order for guardianship and visiting right.
Keeping, all these Constitutional law and harsh ruling by Supreme Court aside, there is a more powerful and important law, the law of nature based on true love, affection and care for each other which cannot be denied by any court or constitution.