Surah 2:225 Allah will not call you to account for thoughtlessness in your oath, but for the intention in your hearts; and he is oft-forgiving, most forbearing.
(Surah 8:58) If thou fearest treachery from any group, throw back (their covenant) to them, (so as to be) on equal terms: for Allah loveth not the treacherous.
Muhammad is God's apostle. Those who follow him are ruthless to the unbelievers but merciful to one another. (Surah 48:29)
Allah will not call you to account for what is futile in your oaths but He will call you to account for your deliberate oaths: for expiation feed ten indigent persons on a scale of the average food of your families; or clothe them; or give a slave his freedom. If that is beyond your means then fast three days. That is the expiation for the oaths ye have sworn. But keep to your oaths. (Surah Maa-ida (5) verse 92)
Like any ideology, such things must be taken together. Clearly, when engaged in jihad, one can easily justify breaking an oath out of "fear" or by virtue of a superceding commitment to war against unbelievers, like me.
A jihadi will do whatever he wants regardless of whether there is an Koran in the courtroom or not. So this debate is not about them, it's about ordinary civil muslims. Would they be more likely to be held to their oath if they swore on a Koran rather than using a Bible or not using any book at all just the oath? From everything posted here and all I can find, it would be a terrible sin for a Muslim to swear on a Koran and then lie. So the bottom line seems to be that the use of a Koran would compel a Muslim to keep to the truth better than not having one. And if that's what it takes to establsih justice in the courtroom, then let them have it.