President Donald Trump has been talking about plans to crack down on undocumented immigration, concerning undocumented immigrants in the U.S. His statement, however, goes back to what "undocumented" actually means according to the law.

While Trump thinks undocumented immigrants are committing crime, the law establishes a clear distinction between improper entry (a federal crime), and mere unauthorized presence in the country (a civil violation). As the law gets laid out, it appears clear that undocumented immigration is not a violation of federal criminal law, but rather a civil violation that gets handled in immigration court proceedings.

According to the Legal Information Institute, the federal law states that it is a crime for anyone to enter into the U.S. without the appropriate approval of an immigration officer. The misdemeanor offense carries fines and not more than six months of imprisonment.

The law doesn't apply to the case of many foreign nationals who enter the U.S. every day and legally, on valid work or travel visas, but end up overstaying for numerous reasons. Findings from a 2006 study proves this, indicating that 45 percent of undocumented immigrants originally entered the U.S. legally, but remained in the country without authorization after their visas had expired.

The appropriate penalty for this type of violation is deportation. The ACLU explains it as "civil removal proceedings that far outnumber criminal prosecutions and remain the primary manner in which the federal authorities enforce the immigration laws".

If, however, an undocumented immigrant is deported due to the violation and returns to the United States without the immigration's authorization, the "undocumented re-entry" will be classified as a federal offense. The individual will then be faced with penalties under the federal law.

Ultimately, it all boils down to the real-time observation of the crime happening within the U.S. While Trump thinks it is the undocumented immigrants who primarily commit crime offenses while in the U.S., studies show that there are exceptions to that, as immigrant crime rates appear lower than those committed by the U.S. born.