Examples of this happening through (Western) history illustrate the tendency for ethical considerations to drive the law: women's suffrage (women's right to vote); the abolition of slavery; and modern human rights and equality legislation are examples of ethical pressures causing change in law.
The independence of nations and the break-up of colonial rule are further examples of ethical pressures overwhelming the force of law.
Unlawful acts are not always unethical. Ethical acts are not always lawful.
Interestingly, the UK Consumer Protection Regulations effective on 26 May 2008 are a good example of unethical business practices becoming prohibited in law. For example it has always been unethical to mislead customers into buying products or services. Now it is illegal to do so (in respect of consumers - here are the implications of the regulations).