Santa Monica Business Attorney.
It sounds like you have two options here. You can either create a partnership agreement which clearly defines each partner's respective roles and rights within the business you have created or you can start the process of forming your own distinct company and terminating your business relationship with your current partner. With both scenarios I recommend that you find a good attorney in your area that will help you to think through all of your rights and responsibilities during the process....
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If you do not have a contract in writing then there is no restriction on whether the claim is litigated or arbitrated. Enforcing and oral agreement may or may not be successful - depending upon what the agreement was for and how much is owed.