Yes, attacking, assaulting, or retaliating against retired federal law enforcement officers is a serious crime. Under 18 U.S.C. § 115, it is illegal to assault, kidnap, or murder—or threaten to do so—any former federal employee or officer with the intent to retaliate against them for the performance of their official duties during their term of service. [1]

Key Legal Details

Retaliation is the Determining Factor: The critical element for applying federal charges is the motive. If the attack is a direct result of their past official duties, federal retaliation laws apply. [1, 2]
Penalties: Depending on the severity of the act, perpetrators can face heavy fines and imprisonment ranging from 1 year for simple assault up to 10 years if the attack involves physical contact or an intent to commit a felony. [1]
State vs. Federal: If the attack is unrelated to their former federal duties (e.g., a random, unprovoked street crime or a personal dispute where their law enforcement background is irrelevant), the attack is still a violent crime, but it will be prosecuted under state and local laws, not federal law. [1]

You can review the full statutes enforced by the U.S. Department of Justice by reading the 18 U.S.C. § 111and 18 U.S.C. § 115 regulations.