The worst thing you could do is enter into a new business arrangement without first consulting a lawyer. This is true whether or not your potential business partner is a friend or a stranger. You need a lawyer to give you specific advice that will help your business succeed and protect you should something go wrong. In this case, it also sounds like you will need a lawyer who has experience drafting international business agreements. I would also recommend that your friend hire his own lawyer to help negotiate whatever specific interests he may have regarding your new business venture. If both of you are represented by counsel, the more likely you are to avoid any misunderstandings regarding your business arrangement.
There is no magic to making any business agreement binding, but you will want an attorney who is knowledgeable about the contract laws of the other country as well as U.S. law to draft the agreement to include terms that will stand up in court here and abroad. In addition to any agreements you need drafted you should also incorporate your business if you have not done so already. A lawyer could give you the best advice on how to legally structure your company. (Take a look at my thoughts on the benefits of incorporating.) Also, if you are doing any kind of business in another country, you will need to think about and take steps to protect your intellectual property such as any trademarks you may want to use. (More on that .)
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