Immigration laws in the United States are some of the most complex in the world. They dictate who can enter the country, how long they can stay, and who can be granted permanent residency. Every year, millions of people apply for US visas online or green cards, hoping to start a new life in the United States. But unfortunately, not everyone who applies will be successful. Certain categories of people are not permitted to enter the US under U.S. immigration law. This blog will look at who these people are and why they are not allowed to enter the country. Read on!