I have a 11 month old son, and his father and I have separated. We have no custody orders in place and I would like to take my son with me on vacation for 4 days to visit family. I have given him all the info for our stay, however he does not want me to take him. Is it illegal for me to take him, and can I loose custody when I come home if I do?

It is not illegal and it is not grounds to lose custody. You have every right to travel with your child as you choose.

Even if you did have a custody order in place, as long as the order didn't specifically prohibit out of state travel and the travel didn't interfere with court ordered visitation, you still could travel.

This is why you affirm custody in court, so questions like this don't occur. The only way you would need his permission is if the travel is out of the country. Don't ask him him. TELL him you are going.