it's easy to say that anyone should have had a written agreement in such circumstances, but the first 4 months of any start up are likely to be hectic and there

it's easy to say that anyone should have had a written agreement in such circumstances, but the first 4 months of any start up are likely to be hectic and there's no time to take out for this kind of thing. Especially when you think you're working with your "friends". Nevertheless, a very clear verbal agreement should have been made. I know this cant be enforced without proof, but it does mean than those involved know the counter-parties also know what they agreed to. it makes things harder to deny. The reason being that, it would be madness to betray each other, just as things start to work. A thing started is far from finished, and they will need everyone and more. Most important of all, it would seem the tech guy legally owns what he has built, in the absence of a proper agreement. Even with a backup copy of this tech, the remaining people aren't likely to be able to extend it easily. The tech guy should consider forming his own startup with the tech he has made.