Paralympic gold medalist Oscar Pistorius has appealed to South Africa’s highest court to cut the sentence he got for murdering his girlfriend, legal documents showed on Tuesday.Pistorious was jailed for six years for shooting dead Reeva Steenkamp - but prosecutors argued that was “shockingly lenient” and an appeals court agreed last month to more than double the term to 15 years.Pistorius filed documents to the Constitutional Court on Monday challenging the appeals court’s ruling.The judgement, he argued, disregarded material findings of the trial court, which showed “compelling circumstances justifying a departure from the prescribed minimum sentence”. Fifteen years is the minimum usually given for murder.Pistorius said this was in breach of his constitutional right to a fair trial and sentencing.When asked about Pistorius’ appeal, Steenkamp’s family spokeswoman Tania Koen said: “It’s his legal right to do so and we have to respect the legal process. It is what it is.”Legal analysts have said such as appeal to the Constitutional Court had slim chances of success.Pistorius’ family spokesman was not available to comment.Rights groups in a country beset by high levels of violent crime against women say Pistorius has received preferential treatment compared to non-whites and those without his wealth or celebrity status. Although in jail, Pistorius has remained in the news. He suffered a bruise in a fight with another inmate after spending too long on a phone call, a prison spokesman said.