The USA PATRIOT Act is an Act of the U.S. Congress that was signed into law by President George W. Bush on October 26, 2001. The title of the act is a acronym, it stands for: Uniting (and) Strengthening America (by) Providing Appropriate Tools Required (to) Intercept (and) Obstruct Terrorism Act of 2001. The Act was passed in the House by 357 to 66 and in the Senate by 98 to 1. The act is a legal normative response to the terrorist attacks of September 11th. Since its passage, several legal challenges have been brought against the act. Actually, the act dramatically reduced restrictions on law enforcement agencies` ability to search telephone, e-mail communications, medical, financial, and other records; eased restrictions on foreign intelligence gathering and deporting immigrants suspected of terrorism-related acts. The act also expanded the definition of terrorism to include domestic terrorism. As a result it enlarged the number of activities to which the Act`s expanded law enforcement powers can be applied. There are many controversies about the constitutionality of the PATRIOT Act. In beginning, many of the act`s provisions were to sunset beginning December 31, 2005. However, following one time reauthorization by President George Bush, on May 26, 2011 President Barack Obama signed a four-year extension of the USA PATRIOT Act. Three key provisions in the Act, ie., roving wiretaps, searches of business records (the "library records provision"), and conducting surveillance of "lone wolves" were also included. Opponents of the law have criticized its authorization of indefinite detentions of immigrants; searches through which law enforcement officers search a home or business without the owner`s or the occupant`s permission or knowledge; the expanded use of National Security Letters. Due to its controversial nature, a number of bills were proposed to amend the USA PATRIOT Act. However no attempts are succeed. As we see, for the past several years, in the immediate aftermath of the attacks of September 11, 2001, both public leaders and legal scholars identified the key challenge of counterterrorism as how best to balance liberty and security, in other words balance between human rights and national security. However as the 9/11 Commission Report itself made clear, the fundamental freedoms of peoples even in open society were not the primary values surpassing national security. Therefor, what lawyers can offer at this stage is some guidance for the rule of law in aiding task of government security activity. From all this points of views, this paper examines the legal character and necessity of U.S.A PATRIOT Act through Controversy and court decision. And the conclusion is that the legal methods against supranational security threats are different those of to general domestic criminal offenses.