In his Luxury Kafka article Cory Doctorow explains how the US government works with regard to immigration:

When you deal with US immigration authorities, everything is elevated to the highest possible stakes. Every step of every process – work visa, green card, citizenship – comes with forms that you sign, on penalty of perjury, attesting that you have made no mistakes or omissions. A single error constitutes a potential falsification of your paperwork, and can result in deportation – losing your job, your house, your kid’s schooling, everything.

It doesn’t only work that way in immigration procedures.

Even if you have American nationality, you can still be treated unfairly, as the victims of FATCA (people with American nationality who do not live in the US) can attest.