Dad and 21 year old  son make a contract. Son is a smoker and Dad is disturbed by this fact. Dad promises to Son if he can quit smoking for one year, Dad will pay Son $5,000. Son quits smoking and does not smoke for whole year. When the Son  inquires  about the  $5,000, Dad says "Son, I got you to quit smoking, this is worth much more that $5,000, therefore, I won't pay you that $5,000." Could son take Dad to court and sue for the contractual obligation? What issues relating to the consideration of the subject matter of the contract are raised here?   4a) Would the outcome of the case be any different if the cigarettes were of marijuana variety?  

It can be said that the son can take his dad to court and sue him for not fulfilling his contractual obligations. If the contract is formed in a state where Marijuana is illegal, the contract can be considered void but if it is legal, the court of law may hear this case based on its legality.

Note: Since the question mentions the amount in dollars, the US federal law and its terms and conditions are applied here and the answer is written accordingly.

A contract can be considered as an agreement between two parties that create mutual legal obligations. It can be oral or written. For a contract to be legally binding, an offer has to be made, there should be mutual acceptance between the parties, a valuable consideration, accepted terms and conditions, and actual performance.

In this case, it can be said that the contract between the dad and his 21-year-old son is a legal contract. It has an offer of $5,000 for quitting smoking for one year, there is a mutual acceptance of the deal and consideration for the father to get his son to stop smoking and the son to get his payment in the form of $5,000. There is also an actual performance from the son. Therefore, it satisfied all the criteria to be a legally binding contract.

Now, since the dad did not hold up his end of the bargain on the actual performance, it can be said that the son can take his dad to court and sue him for not fulfilling his contractual obligations. The son was supposed to get $5,000 from his dad for quitting smoking for a year but he did not and since the contract is legally binding, he can sue his dad for non-performance.

Consideration is what can be defined as what each party benefits from a contract. The consideration in this case for the son was that he will get $5,000 for quitting smoking for one year and the dad's consideration was getting his son to quit smoking. Dad got his consideration fulfilled in the contract but the Son did not have his consideration fulfilled as stated in the subject matter of the contract.

In case, the cigarettes were of marijuana variety, the controlled Substances Act under the federal law can come into play. But the state where the contract is formed is also vital too. Because there are states in the U.S.A, where Cannabis is fully legalized and states where is not.

Therefore, if the contract involved cigarettes of marijuana variety, and it was formed in a state where Marijuana is considered illegal, the contract can be considered void in the court of law but if it is in a state where Marijuana is legal, the court of law may hear this case based on its already established circumstances.