The Crown Prosecution Service has said it cannot prosecute a UAE government minister over claims he sexually assaulted a Hay Festival organiser in Abu Dhabi.
Festival employee Caitlin McNamara alleged she was attacked by Sheikh Nahyan bin Mubarak Al Nahyan on a private island in February.
The CPS said it could not bring charges because the alleged offence happened abroad.
Sheikh Nahyan denies the allegations.
Ms McNamara, 32, who has waived her right to anonymity, had been visiting the United Arab Emirates for discussions about holding Hay's first event in the Middle East.
She claims she was attacked by the Minister of Tolerance, who is a member of the ruling family in Abu Dhabi, during a meeting to discuss human rights concerns ahead of the festival.
Ms McNamara had been seeking a prosecution in the UK, but CPS senior prosecutor Jenny Hopkins said no charges could be pursued.
She said this was because the alleged offence happened outside the UK and the circumstances did not allow a prosecution in the UK.
"I understand this is not the outcome the complainant wanted, but the CPS must ensure that the law is properly applied, and make fair, objective and independent decisions in every case," she said.
The CPS considered whether it could prosecute in the UK under laws allowing foreign nationals to be charged with torture.
However the service concluded that under law it would have to show the defendant was a public official who inflicted "severe pain and suffering" while carrying out official duties.
The CPS said: "We took into account the complainant's belief that she was attending a meeting about work when she agreed to meet with the suspect.
"However, her understanding of the nature of the meeting is not sufficient by itself to prove that the suspect was purporting to act in the performance of his official duties.
"From the evidence, the suspect's conduct in arranging the meeting and during the meeting, suggest the contrary, that he considered this to be a social meeting and did not want to discuss work.
"In those circumstances we cannot prove an essential legal element, namely that the assault was committed in the purported performance of the suspect's public duties and consequently amounts to torture."
Ms McNamara has the right to challenge the decision by asking for a review.