Tax avoidance is the legal usage of the tax regime to one’s own advantage to reduce the amount of tax that is payable by means that are within the law. Tax sheltering is very similar, although unlike tax avoidance tax sheltering is not necessarily legal. Tax havens are jurisdictions which facilitate reduced taxes. The term tax mitigation is sometimes used; its original use was by tax advisers as an alternative to the pejorative term tax evasion. “Tax aggressive” strategies fall into the grey area between commonplace and well-accepted tax avoidance (such as purchasing municipal bonds in the United States) and evasion. However, the uses of these terms vary. Laws known as a General Anti-Avoidance Rule (GAAR) statutes which prohibit “tax aggressive” avoidance have been passed in several developed countries including Canada, Australia, New Zealand, South Africa, Norway and Hong Kong. In addition, judicial doctrines have accomplished the similar purpose, notably in the United States through the “business purpose” and “economic substance” doctrines established in Gregory v. Helvering and in the UK through the Ramsay case. Though the specifics may vary according to jurisdiction, these rules invalidate tax avoidance which is technically legal but not for a business purpose or in violation of the spirit of the tax code. Related terms for tax avoidance include tax planning and tax sheltering. The term avoidance has also been used in the tax regulations [examples and source needed] of some jurisdictions to distinguish tax avoidance foreseen by the legislators from tax avoidance which exploits loopholes in the law such as like-kind exchanges. The United States Supreme Court has stated that “The legal right of an individual to decrease the amount of what would otherwise be his taxes or altogether avoid them, by means which the law permits, cannot be doubted.” Tax evasion, on the other hand, is the general term for efforts by individuals, corporations, trusts and other entities to evade taxes by illegal means. Both tax avoidance and evasion can be viewed as forms of tax noncompliance, as they describe a range of activities that are unfavorable to a state’s tax system.