Virtually all restrictions on voting have in recent years been implemented by Republicans. Republicans, mainly at the state level, argue that the restrictions (such as purging voter rolls, limiting voting locations, and prosecuting double voting) are vital to prevent voter fraud, claiming that voter fraud is an underestimated issue in elections. However, research has indicated that voter fraud is very uncommon, as civil and voting rights organizations often accuse Republicans of enacting restrictions to influence elections in the party's favor. Many laws or regulations restricting voting enacted by Republicans have been successfully challenged in court, with court rulings striking down such regulations and accusing Republicans of establishing them with partisan purpose.