Yes, you may be able to buy a life insurance policy on your brother if you have an 'insurable interest" in your brother.

Insurable Interest means that there is some sort of financial link between you and your brother. Either you rely on him for some financial support, or you may suffer financially if he were to die.

Your brother would, of course, need to cooperate in the process, sign the application for life insurance and provide medical information.  There are many circumstances in which purchasing life insurance on your brother may make good sense.

For instance, if your brother supports you financially, is a partner in your business, or you would be the one handling your brother's burial and funeral if he were to die. In addition, if he has children and you would be the guardian of his kids upon his passing, you may want to insure his life so you have the funds needed to provide for raising his children. 

Here's how you may purchase life insurance direct online.