An Alabama judge has upheld key parts of the state's immigration law, which is widely considered to be the toughest law on undocumented workers in the nation.

U.S. District Judge Sharon Blackburn ruled that Alabama can enforce the law's requirement for public schools to verify the citizenship status of its students and report statistics to the state, a measure that opponents -- such as immigrant support groups and even the Obama administrator -- argue is designed to decrease enrollment of immigrant children by creating a climate of fear. However, the law does not bar illegal immigrants from attending public schools.

In her 115-page opinion on the case, The Associated Press reports that Blackburn stated some parts of the law are in conflict with federal law, but others -- such as the public school requirement -- are not.

Blackburn wrote that other provisions that are not prohibited by federal law, and have therefore also been upheld, include one which allows police to hold suspected illegal immigrants without bond. She also upheld a measure to bar state courts from enforcing contracts involving illegal immigrants, one which makes it for an illegal immigrant to do business with the state, and another that makes it a misdemeanor for an illegal resident to not carry immigration papers.

Blackburn's order temporarily blocked four parts of the law, including making it a crime for an undocumented worker to solicit work as well as making it illegal to transport or harbor an illegal resident.  The judge is also reconsidering provisions that allow discrimination lawsuits against companies that lay off legal workers and then hire undocumented workers and forbid businesses from claiming tax deduction on wages paid to individuals who are in the country illegally.

Although Blackburn did not specify when the upheld portions of the law will take effect, her previous order that blocked its enforcement expires on Thursday. The AP reports that neither Gov. Robert Bentley nor Alabama Attorney General Luther Strange immediately commented on when the state would begin enforcing the law as of Wednesday afternoon.

Alabama's Hispanic population has grown steadily over the last decade, with individuals of Hispanic or Latino origin making up almost 4 percent of state residents in 2010, according to the U.S. Census Bureau. The Pew Hispanic estimated there were 130,000 illegal immigrants living in Alabama in 2009, up from 100,000the year before.

A series of less-restrictive immigration enforcement laws have been passed in a number of other states, including Arizona, Utah, Indiana and Georgia, although federal judges have either blocked the entire measures or at least portions of it.

Multiple parties, including the Obama administration, bishops from Alabama's Catholic, United Methodist and Episcopal Churches and civil rights organizations such as the American Civil Liberties Union and the Southern Poverty Law Center, filed lawsuits against the Alabama law, leading Blackburn to issue a temporary hold on it in August. As of now, the court has only ruled on the motions filed by the Department of Justice and the church groups.