>lawmakers can create new laws which can not be applied retroactively Still a courtesy:

    Background: Mary Anne Gehris was born in Germany and came to the United States around age 1, growing up entirely in the U.S. as a lawful permanent resident (green card holder). 

    Immigration Consequences: Years later, under the **Illegal Immigration Reform and Immigrant Responsibility Act of 1996 **(IIRIRA)—enacted during the Clinton administration but actively enforced during the Bush Jr. administration—her misdemeanor battery conviction was classified as an "aggravated felony" under federal immigration law. This made her deportable despite having no subsequent criminal record, being married to a U.S. citizen, and having a U.S. citizen child. 

Source Coverage: The story was detailed in Anthony Lewis's New York Times columns:

    "Abroad at Home: 'This Has Got Me in Some Kind of Whirlwind'" (January 8, 2000)

These columns highlighted how IIRIRA's broad definition of "aggravated felony" swept up many long-term permanent residents with minor, often decades-old convictions, separating families and deporting people who had lived nearly their entire lives in the United States.

The Gehris case became a frequently cited example in immigration advocacy and legal scholarship about the harsh consequences of mandatory deportation provisions for lawful permanent residents. If you'd like, I can search for the original NYT articles or additional reporting on her case.

This is easy. Have your own standards based on your own reason and navigate any arbitrary standards LCD majority of the society cooks up from time to time.