I'm asking this for a friend. She and her XP have a baby son, they split up reasonably amicably when he was a couple of months old. Up til now they have had an informal arrangement where he pops in to see his son when he wants, or takes him when she wants a break.
They have fallen out now over something unrelated to their child, and the XP is very angry with her. He is threatening to take her to court to get joint custody, and has even told her he wants to do a month the baby staying with him, then a month with her.
What's the likely outcome if he does take her to court? What rights does he have over access? They aren't married, XP is named on the birth certificate, and he pays no maintenance.