My daughter has custody of her son. The father and she were never married. I want to bring my grandson to visit with me for the summer but the father says no longer than a week or he will come and take him back. Do I need a letter of consent from the father for this? I don't want him and the police on my doorstep taking my grandson away.

Do I need a letter of consent from the father for this? I don't want him and the police on my doorstep taking my grandson away.

Short answer-yes.

Does your daughter have sole legal and physical custody or is it joint legal custody? Does he have visitation? If he does, then anything that interferes with his visitation he can veto. Your daughter (not you) can go to court for permission, but it may not be granted.

Agree, the father, if he has court ordered visitation can not have his visits limited. So if the child was to be out of state or not available for visits for a long period, the father has to give him permission. Often agreement for a longer visit at another time can be worked out. Perhaps he would get the child for a full month or something after the child comes back, but he would have to agree to it

My daughter has custody of her son. ...
Do I need a letter of consent from the father for this? ...
Is father on the birth certificate?

Assuming the mother has court-ordered full custody, and the father has no court-ordered visitation, no. If he is on the BC, and there is no court order in place, yes. But if there is a question, you should have a letter from the mother. Get it notarized, in case there is any question as to whether she was the one who signed it.