曾几何时，这样的契约由武力干预来强制实施，墨西哥、委内瑞拉、埃及和其他一些国家在十九世纪和二十世纪初以沉重的代价学到了这一教训。
Once upon a time, such contracts were enforced by armed intervention, as Mexico, Venezuela, Egypt, and a host of other countries learned at great cost in the nineteenth and early twentieth centuries.