Legislators in Justin Timberlake's native Tennessee have amended a law banning selfies at polling stations, six months after the superstar fell foul of the rule during the U.S. presidential election.

The SexyBack hitmaker returned home to Memphis and snapped a seemingly-innocent picture as he cast his early ballot for Democrat Hillary Clinton in October (16), but he soon learned the photo he posted on social media was in violation of a new law introduced in 2015.

The ruling prohibits voters from taking photos or recording conversations while voting, with offenders facing the possibility of 30 days behind bars and a fine if caught breaking the law.

The District Attorney in Shelby County, Tennessee declined to prosecute Justin for the misdemeanour, and last week (ends14Apr17), authorities in the state Senate created a new bill, which will "allow photographing or video-taping a filled-out ballot, except if it's intended to commit voter intimidation, voter fraud, or sell a vote".

Justin has yet to comment on the legislation change, which he had no idea about at the time of his voting blunder last year.

"No excuses, my good people!," he wrote beside his selfie. "There could be early voting in your town too. If not, November 8th! Choose to have a voice! If you don't, then we can't HEAR YOU! Get out and VOTE!"

He then laughed off his mistake days later as he joked around with his pal, TV presenter Jimmy Fallon, who asked what he had been up to.

"I recently voted. Super quiet, under the radar," the singer/actor smiled during an appearance on America's The Tonight Show Starring Jimmy Fallon. "Went home to Tennessee and voted. Super quiet, in and out. No one even knew."