You can buy a life insurance policy on your brother if you have an “insurable interest” in his life. 

This could include being his custodian if he is not yet an adult, or handicapped, being his business partner, being responsible for his outstanding debts, and other scenarios. 

It would be challenging to think of an instance when you would be denied the privilege of insuring your brother.  Of course, your brother has to cooperate. This means, he will need to answer some...