Sixteen-year-old Lydia Playfoot went to the High Court claiming that her school was discriminating against her by not allowing the wearing of a "purity ring".
Young people must complete a course before wearing the ring
Started in the US, the Silver Ring Thing is the organisation behind the symbol of her pledge to sexual abstinence.
"God wants you to be holy, so you should keep clear of sexual sin. Then each of you will control your body and live in holiness and honour."
This verse from the New Testament book of 1 Thessalonians 4:3-4 is the basis of the belief in sexual purity and abstinence among young people of the Silver Ring Thing (SRT) movement.
The city of Yuma, Arizona, was the birthplace of SRT, founded by Denny and Amy Pattyn in 1996.
It was their response to what they saw as a worrying rise in the number of pregnancies among teenage girls.
In the UK, SRT is based in Horsham in West Sussex and run by a group of volunteers.
Lydia Playfoot took her case to wear the ring to the High Court
It is headed by its managing director Andy Robinson, who is the full time youth pastor at King's Church, Horsham.
He was the sales director of an international software company until December 2005.
The group was established in the UK following the 2004 BBC Two documentary American Virgins, which looked at programmes promoting sexual abstinence in the US.
How far can I go?
SRT stresses that the silver ring worn by the young people who pledge to sexual abstinence is "not a piece of jewellery".
In the UK, they must complete the SRT434 programme, which aims to inform small groups of both female and male teenagers about the "blessings of sexual abstinence".
There are four parts to the course - Temptation, How far can I go?, Consequences, and How can God help me?
Once they have completed the course they are able to wear the SRT ring.
The organisation uses DVDs, discussion groups and bible studies to "communicate the risks associated with teen sexual activity, social pressures and the blessings of sexual abstinence".
According to SRT: "Those who go through the programme will be motivated and better prepared to take a strong stand for sexual abstinence during difficult and tempting situations."