President Bush Thursday is expected to sign into law an extension of the anti-terrorism USA Patriot Act.  

Congress gave final approval to the legislation earlier in the week, after months of political battles over contentious parts of the law.

The Patriot Act was first enacted after the September 11, 2001 terrorist attacks on the United States.  It gives investigators broader powers to seize library and medical records as well as to conduct roving wiretaps.

Critics say the law threatens civil liberties.  Lawmakers debated how to balance fighting terrorism and protecting Americans while respecting the rights of private citizens.

Sixteen provisions of the law were due to expire Friday.  The new bill makes most of those provisions permanent, while it imposes certain restrictions on what the Patriot Act allows officials to do.

Some information for this report was provided by AP.