Be consistent....be consistent....be consistent. If you even just one time don't follow through with a punishment, you hand the power over to him. If he knows there's even a slight possibility that you won't follow through, he'll continue to do the bad behavior. If you make up a chart or just a mental note of a punishment that's given everytime, he will learn the idea of consequences. If time out doesn't work, find a toy that you can take away for the day. At bedtime, let him cry and fight it out. If you don't pay attention to the behavior, it's the same as staying in control. Remind yourself when you're trying to argue with him and talk him into going to bed that you're trying to compromise with a three year old, and that just isn't going to happen. It's easy to say that the children are the problem and must have something such as ADD, but I truly believe that it's us as parents that either raise well behaved, disciplined children, or we raise kids who don't pay attention, don't respect people, don't listen, and act out of control. I'm not saying that we do this intentionally, we just get tired of constantly disciplining and so we begin to let them get away with behavior now and then. Before we know it, they're out of control and then we're saying that we think something is wrong with them.
I do not believe for one second that this is a phase. I think that it will get progressively worse if you don't gain control back as a parent and make them know that you're the one in charge, not them. I realize that there is probably ADHD a lot out there, but I can't help but think about how when we were kids and our parents were kids, there was no such thing and my mom and grandma say that they weren't around a lot of kids that they would say were ADHD, just kids that needed some good discipline. I really really don't agree with starting young children on medications early on in life. How are they supposed to become themselves as they grow if they have medication constantly making them feel a certain way or not feel a certain way?