Specifically, the Patriot Act
Allows the government to enter and search your home, without ever informing you. The U.S. Constitution requires not only probable cause to search, but that you be notified of the search. This law- Section 213 of the Patriot Act -- circumvents the notice requirement of the 4th Amendment.
Section 216 of the PATRIOT ACT allows the government to tap your phone and computer without probable cause. Under this section, a judge MUST rubber stamp a warrant as long as law enforcement certifies that the surveillance is "relevant to an ongoing criminal investigation." No probable cause of
criminal activity is required to issue the warrant. This violates the probable cause provision of the 4th Amendment.
Further, Section 218 allows the government to carry out secret searches and wiretaps without showing probable cause merely by certifying that there is a "significant" foreign intelligence purpose. This also evades the 4th Amendment.
Section 802 creates the crime of "domestic terrorism." This criminalizes acts that "appear to be intended" to "influence the policy of the government by intimidation or coercion" or to "intimidate or coerce a civilian population."
This section would make just about any act of civil disobedience in protest against government policies into an act of domestic terrorism.
Section 411 in tandem with section 802, expands the power of government to designate a group a "foreign terrorist organization." Any group which endorses so-called "terrorist activity," which under 802 may be otherwise lawful protest activity, can be designated a terrorist organization. This would enable government to designate such groups as the protestors at Vieques, Puerto Rico, or those against the World Trade Organization.
Section 411 also allows the government to indict anyone who provides material support or assistance to a terrorist organization. If you provided humanitarian or medical assistance to the Northern Alliance - foes of bin Laden - you could be arrested for supporting terrorism.
Finally, Section 412 of the PATRIOT Act permits the government to arrest and detain immigrants indefinitely for nothing more than a visa violation. In fact, of the 1200 known immigrant detentions since 9/11, the ACLU determined that only about five were detained on terrorism-related charges. Because the Department of Justice refused to release any information, the ACLU obtained this information from foreign embassies to whom the DOJ had courteously supplied the information where it affected one of their citizens.
Thus, what is too sensitive to show to Americans, the Department of Justice has no problem revealing to Islamic nations.