James Madison--the fourth president of the United States and principal author of the U.S. Constitution--once wrote, “...that as they [aliens], owe, on the one hand, a temporary obedience, they are entitled, in return, to their [constitutional] protection and advantage.” So do not let the fact that the term “illegal” or “undocumented immigrants” lead you to believe the Constitution’s rights and freedoms do not apply to them.
Rights that Protect Illegal Aliens
According to Section One of the 14th Amendment to the Constitution, “No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.” In the U.S. Supreme Court case called Zadvydas v. Davis (2001), that “due process” applies to all aliens in the U.S. whose presence maybe or is “unlawful, involuntary or transitory.”
Decades before that case, the court ruled in Almeida-Sanchez v. United States (1973) that all criminal charge-related elements of the Constitution's amendments, such as the First, Fourth, Fifth, Sixth and the 14th) protect non-citizens, legally or illegally present.
The First Amendment prevents the government from censoring non-citizens speech or suppressing the practice of their religion. The Fourth Amendment protects them against unreasonable search and seizure. The Fifth Amendment ensures that non-citizens property can only be taken by the government for a public, along with compensation. The Sixth Amendment includes the right to a jury trial, the right to counsel, and protection against self-incrimination.
While undocumented immigrants have several constitutional protections, there are three exceptions: voting, some government jobs, and gun ownership.