From a legal point of view, this second part is not required, in a unilateral treaty, to actually accomplish the task and cannot argue as an offence, because it does not do so. If it is a bilateral treaty, both parties would have a legal obligation. In more complex situations, such as multinational trade negotiations, a bilateral treaty can be an “incidental exchange.” In other words, both parties are involved in the general negotiations, but may also recognize the need for a separate treaty that is relevant only to their common interests. You must also prove the same criteria if you decide to apply a bilateral or unilateral treaty to the courts. In all situations, you will find that a bilateral agreement is an agreement between two parties, in which each party agrees to fulfill its side of the bargain. In the real world, Eric will probably say, “Dan, are you going to paint my fence for $150?” Since it is not known whether it is a bilateral or unilateral treaty, the law allows Dan to accept it, either by painting the fence or by promising to paint the fence in the future. To accept, Dan must either start painting the fence or tell Eric that he`s going to paint the fence. In this case, the offer is presumed to foreshadow a bilateral agreement. In general, if one does not know what kind of response is expected, one can assume that a bilateral contract is expected because people generally do not want to be related, unless the contract offerer is also bound.  At first glance, the most obvious difference between bilateral and unilateral treaties is the number of people or parties who promise action. Bilateral agreements require at least two, while unilateral contracts must be only partial. For example, if someone offered to drive you to work on Mondays and Tuesdays in exchange for your promise to return favors on Wednesdays and Thursdays, a bilateral contract would bind you as soon as you thought about those conditions. But if the same person offered to pay you $10 a day that you would take him to work, a unilateral contract would be formed, which would only hire the promisor until you took him to work on a given day.
Examples of bilateral treaties exist in everyday life. You enter this type of agreement every time you buy from your favorite store, order a meal in a restaurant, treat your doctor or even see a book in your library. In any case, you promised a particular action to another person or party in response to the action of that person or party.