A US sex trafficking victim jailed for life as a teenager for shooting a man who had paid to sleep with her has been granted clemency by Tennessee Governor Bill Haslam.

Cyntoia Brown, 30, was only 16 when she was convicted of shooting and killing real estate agent Johnny Allen, who had picked her up for sex at a restaurant in East Nashville before taking her back to his home.

Brown, who had been forced to work as a prostitute by her pimp boyfriend after she ran away from home, claimed she was in fear of her life when she killed Allen, arguing that she believed he was going to shoot her if she did not act first.

She was handed a life sentence after being tried as an adult in 2006 after prosecutors argued she had murdered Allen in cold blood before stealing his gun, money and a car.

Over the past 15 years, campaigners have argued that Brown should have been treated as a victim rather than a killer, not only on account of the fact that she had been forced into sex work, but also because she lacked the mental capacity to be criminally culpable for her actions as she was born suffering from foetal alcohol syndrome.

She will now be released from jail in August, after which time she will spend 10 years on parole under supervision to ensure she does not break any state or federal laws, obtains and holds down a job, and participates in regular counselling sessions.

Explaining his decision to grant clemency in a statement, Haslam said: “Cyntoia Brown committed, by her own admission, a horrific crime at the age of 16.

“Yet, imposing a life sentence on a juvenile that would require her to serve at least 51 years before even being eligible for parole consideration is too harsh, especially in light of the extraordinary steps Ms Brown has taken to rebuild her life.”

Speaking through her legal team, Brown thanked Haslam for his decision to free her, adding: “I am thankful for all the support, prayers, and encouragement I have received.”

Numerous celebrities who had campaigned for Brown’s release took to social media after Haslam’s clemency statement was made, with Kim Kardashian West, Alyssa Milano and Sophia Bush posting on their Twitter profiles to thank the governor for his decision.

Stacey Abrams, who became the first black female nominee for governor in the US during the mid-term elections, tweeted: “Justice has finally been served: #CyntoiaBrown has been granted clemency.

“This victory belongs to Cyntoia Brown & to the Tennessee human trafficking activists, especially Black women, who refused to concede injustice & instead organized to create change.”