Common problems with Utilitarianism are that the doctrine is impossible, impractical, and also doesn't benefit minorities. Utilitarianism is a non-religious doctrine that is based on undergoing actions that add the greatest utility or benefit to the majority of the population. Utilitarianism was founded by Jeremy Bentham and the doctrine was further developed by John Stuart Mill.
The problem with utilitarianism is that its impossible because the happiness of an individual cannot be measured. Happiness is not measurable thing like wealth or poverty because its innate, hence it's not an adequate system to operate on. Another problem with utilitarianism is that it is very difficult to apply. Countries like the United States are not comprised of homogeneous groups, but are full of diverse individuals from different faiths and backgrounds. Utilitarian policies lead to favoritism and further sows discord among groups of people.
Additionally, utilitarianism acts in the best interest of the majority, and because minorities are little in number, their rights are not of great importance. Hence utilitarianism justifies racist and unfair legislation as long as it maximizes the happiness of the majority of the population. Utilitarianism doesn't mean fairness because fairness is ensuring that all groups are treated equally, while utilitarianism only focuses on the largest group.