There is a lot of misunderstanding about how the crime of rape is established within an Islamic judicial system. Many people are of the false opinion that four witnesses must see the act of rape in order for a conviction to hold in the courts. They are understandably appalled by the idea that a woman who cannot produce four witnesses to the crime will be unable to bring justice to bear on her attacker. Nothing could be further from the truth.
It is true that the prescribed punishment (hadd) for fornication requires four witnesses in order for that specific punishment to be a sacred duty for the Muslim courts to carry out. However, what it means is that, in the absence of four witnesses, the judge will prescribe a punishment for the perpetrator according to his discretion or according to the country's penal code. He will not be obliged to prescribe the specific prescribed punishment for fornication. In any case, rape is a far more serious matter than fornication and deserves a more severe punishment.
It is important to clarify a common misconception that many people have about the judicial system in a state that operates within the parameters of Islamic Law. It is commonly assumed that every decision and every criminal sentencing in an Islamic country is derived directly from Islamic religious teachings and from sacred law. This is not the case at all.
A court operating under Islamic Law will be obliged to carry out Islamic legal injunctions in the few instances where those injunctions are relevant. Otherwise, the judicial decisions of the court will be based upon the court's application and interpretation of the country's statutory law and on the discretion of the judge, as it is with purely secular legal systems.
In Islam, there are a handful of crimes that are addresses by the sacred texts and are given prescribed punishments (hudûd in Arabic). The same texts determine the evidentiary burden that is required to establish guilt. When this evidence is established, it becomes the religious duty of the courts to carry out the sentence. There are only a few crimes of this nature. Even with these crimes, if the burden of evidence is not met for the prescribed punishment to be carried out, then it will not be obligatory upon the courts to carry out that specific prescribed punishment.
Instead, the matter reverts to the discretion of the court. It becomes, like any other crime, a matter for the court to decide on its own authority or for the country's legal system to determine through statutory legislation. The discretionary punishment (ta`zîr in Arabic) might be a protracted prison sentence, or even the death penalty.
We can see an example of this in the law that the Muslim scholars in Saudi Arabia have approved of, where the death penalty is decreed by statute for drug smugglers who bring large quantities of drugs into the country. No punishment for drug smuggling is mentioned in the Qur’ân and Sunnah. This is a discretionary punishment set by statute.
The courts and the civil law codes can also determine the evidentiary burden needed for a conviction. This may include circumstantial evidence, any number of male or female witnesses, DNA evidence, and so forth.
The vast majority of civil and criminal cases heard by the courts in an Islamic country will not be decided on the basis of scriptural teachings. In the vast majority of criminal cases, the definition of crimes will be determined by the country's statutory laws, which are developed through the country's legislative process. Likewise, sentencing will either be dictated by statute or passed according the judge's discretion. This is very similar to the situation in the judicial systems of secular countries.
In the secular courts of the West and other parts of the world, they do not have any such thing as divinely prescribed punishments. All punishments are determined by the discretion of the courts or by the country's statutory penal law. Still, rapists are punished for their crimes. The same can be said for the courts in an Islamic legal system. The matter reverts to the discretion of the courts in the absence of the specific evidence required for carrying out the prescribed punishment.
And Allah knows best.