A federal judge ruled Wednesday that the most controversial pieces of Arizona's signature immigration law can now go into effect, thus clearing the way for the contentious legislation to finally kick in after a protracted legal battle of its implementation.

That measure, dubbed the "show me your papers" provision, allows law enforcement officers to demand identification that proves citizenship or immigration status while questioning suspects. Critics of the provision contend that it institutionalizes racial profiling, saying officers could stop someone for any reason, whether they truly suspect a crime or not, and that legal residents without proper identification on them could then be unjustly arrested.

The ruling, by U.S. District Judge Susan Bolton , ends a two-year legal battle over the law, known as SB 1070. Back in June, the Supreme Court struck down parts of the law, but allowed some of the more contentious aspect of it, including the papers provision, to stand. Opponents of the law then asked Bolton to block the provision, something she declined to do in her ruling.

Arizona passed the law in 2010, and aspects of the law have been in place since that year. At least five other states, including Georgia, Alabama and South Carolina, all subsequently pursued similar legislation.

Arizona Gov. Jan Brewer (R) was a forceful advocate for the law, saying that her state had to act because the government had failed to do so.

"The bill I'm about to sign into law—Senate Bill 1070—represents another tool for our state to use as we work to solve a crisis we did not create and the federal government has refused to fix: the crisis caused by illegal immigration and Arizona's porous border," Brewer said in a statement at the time of the bill's signing.