to the double jeopardy clause.
The specific facts of the case are that in 2008, Terance Gamble was convicted of second-degree robbery in Mobile County, Alabama, resulting in his being barred under federal and state law from possessing a firearm in the future.
More than seven years later, Gamble was driving in Mobile when a police officer pulled him over for a faulty tail light. Smelling marijuana coming from Gambles car, the officer searched the vehicle and discovered two baggies of marijuana, a digital scale, and a 9mm handgun.
The state of Alabama prosecuted Gamble for possessing marijuana and for being a previously convicted felon in possession of a firearm. Gamble received a one-year sentence, which he finished serving on May 14, 2017.
While the Alabama prosecution was ongoing, the federal government charged Gamble for the same offense under federal law: being a felon in possession of a firearm. In other words, the federal government based its prosecution on the same incident on November 29, 2015 that gave rise to his state court conviction. Gamble thereupon was convicted and sentenced to nearly four years in prison -- meaning that he now faced the prospect of being imprisoned for around three more years after he had served his one year state conviction sentence.
Because this is a clear cut case of the same facts being the basis of two separate prosecutions for the same offense, the resolution of the case will not necessarily resolve is the more difficult question of when two prosecutions are considered to arise from the same facts and be based on identically (or nearly identically) defined offenses.
Finally, as has been pointed out several times on other threads, the impetus for the SCOTUS to take this case came from Justice Ginsburg who, together with Justice Thomas, has suggested that the time has come to re-examine the separate (or dual) sovereigns exception to the double jeopardy clause.