The example of Muslim traders illustrates this well. Participation in a contract or company that involves charging and obtaining riba or interest is strictly prohibited under Islamic law. Muslims are, however, permitted to trade currencies. There is a belief that this is due to teaching attributed to the Prophet Muhammad.
In order to allow traders to trade regardless of their beliefs, swap-free accounts were developed. Forex trading and these accounts are still being debated as to whether they are actually halal. For Muslim traders, the decision ultimately rests on whether they believe that a swap-free account adequately satisfies the riba prohibition.