Immigration law in any country is very complicated and the US is no exception. Someone who has come to the US and wants to stay here permanently can find it very difficult to work out if they have the right to do so. Even once someone has identified the fact that they can indeed live legally in the US getting all of the necessary paperwork together and getting it approved is not easy.
Without a doubt, anyone who wants to become a US citizen needs help. They need someone who fully understands the rules and regulations.
On paper, anyone who has studied immigration law could potentially help. However, in reality, simply understanding what the law says and the processes that need to be followed is not enough. Anyone who wants to legalize their residence status needs the help of someone who is familiar with how the system actually works. This kind of lawyer will know the quickest way to take an application through the system. They will understand how to avoid misunderstandings and the delays that often result from forms not being filled out clearly enough.