Most news outlets are reporting that Zach Scruggs pleaded guilty to misprision of felony by simply failing to report the “conspiracy” to influence Judge Lackey. The Daily Mississippian says “Zach Scruggs pleaded guilty to failure to report a conspiracy by his father and law partners to bribe Mississippi Circuit Court Judge Henry Lackey earlier this year.” The Clarion Ledger states “In March, Zach Scruggs pleaded guilty to misprision of a felony, which means he had knowledge of a felony but didn’t report it.” The Sun Herald says “Zach Scruggs has been sentenced to 14 months in prison for knowing about a Mississippi judicial bribery scandal and not reporting it to authorities.”
“Misprision of Felony” is still an offense under United States federal law after being codified in 1909 under 18 U.S.C. § 4:
Whoever, having knowledge of the actual commission of a felony cognizable by a court of the United States, conceals and does not as soon as possible make known the same to some judge or other person in civil or military authority under the United States, shall be fined under this title or imprisoned not more than three years, or both.
This offense, however, requires active concealment of a known felony rather than merely failing to report it.
There is a footnote to that wikipedia comment that states this:
See United States v. Johnson, 546 F.2d 1225 (5th Cir. 1977) at 1227 (“The mere failure to report a felony is not sufficient to constitute a violation of 18 U.S.C.A. § 4.”