re: French drain / property law question

He's aware of my problem. We've just hit a snag in regards to him agreeing to allow me to tap into his line. He "just doesn't think it's a good idea" and that "I should run another line here". Here not being the low spot between our homes, instead here being on my property so I don't have to bother his line. He's just being a little difficult at the current moment and I was curious about what property law says about a French drain being on the property line. Common sense says I'm entitled to it since it's the property line. I'm just not sure if that's correct since he paid to have the line installed.