What are the legal implications of Jailbreaking an iOS device? I am forced to Jailbreak an iPad so that I can deploy a custom application for a client. This is an application that no one can have but him, so basically jailbreaking is the only choice I have?

I can't even install the app as a demo through the provisioning profile because that expires I think in 1 year?

What legal implications, in various jurisdictions, are there for jailbreaking an iOS device?
You can use a provisioning profile as long as he gets a new provisioning profile before the current one expires.

Apple also has a business store (basically a corporate App Store) but I think that is way over the top for what you are trying to do.

The most legitimate/safe option is to deploy a provisioning file and update it each year…