When a business partnership goes awry, one thing that sometimes gets overlooked is who gets the business' domain name.
If one partner is keeping on with the business, chances are they assume the domain is owned by the business. This is not always the case.
When a domain is registered, it's often registered by an individual in their own name (the "registrant"). In this case, the registrar (company through which the domain was registered) has a legal agreement with the registrant. If that individual leaves the business, they can be nasty and take the domain with them.
My suggestion: if you're forming a business partnership, register the domain for the business in the company's name. That way if there's ever a split in the partnership, if one partner is planning to continue the business, they will still have legal access to the domain.
Disclaimer: This is what I've learned from my experience, but I'm not a lawyer. You may want to consult one to get more clarification on this isssue.