Even though a prior State offense may be a predicate crime for a new federal offense, where the person is no longer in State custody for the prior offense, they cannot bring a federal habeas corpus proceeding pursuant to Section 2254(a), the U.S. Supreme Court held April 26 in Alaska v. Wright.
18 U.S.C. Sec. 2254(a) provides that a district court “shall entertain an application for a writ of habeas corpus on behalf of a person in custody pursuant to the judgment of a State court.”
In 2009, Sean Wright was convicted of a sex offense in Alaska.  He finished serving his sentence in 2016, and moved to Tennessee.
Once there, he failed to register as a sex offender under federal law, and was ultimately convicted and sentenced for failure to register.    
During the course of the failure to register case, Wright filed a habeas corpus action in U.S. district court in Alaska, challenging his 2009 conviction on grounds that Alaska courts had unreasonably applied federal law in denying various Sixth Amendment claims.
The district court denied the motion on grounds that Wright was not “in custody pursuant to the judgment of a State court.”
The Ninth Circuit reversed on grounds that Wright’s state conviction was a “necessary predicate” to his federal conviction, so Wright was in custody pursuant to the judgment of a state court.
The Supreme Court reversed, in an unanimous per curiam opinion.
The Court had previously held that a habeas petition does not remain “in custody” under a conviction “after the sentence imposed for it has fully expired, merely because of the possibility that the prior conviction will be used to enhance the sentences imposed for any subsequent crimes,” the Court said.
“That Wright’s state conviction served as a predicate for his federal conviction thus did not render him ‘in custody pursuant to the judgment of a State court’ under Section 2254(a),” the Court said.  
“If Wright’s second conviction had been for a state crime, he independently could have satisfied Section 2254(a)’s ‘in custody’ requirement … though his ability to attack the first conviction by that means would have been limited,” the Court said.  
“Wright could not satisfy Section 2254(a) on that independent basis for the simple reason that his second judgment was entered by a federal court,” the Court concluded.