Civil rights groups challenging Arizona's 2010 immigration law are asking a judge to force the law's chief sponsor to turn over all his emails and documents about the contentious statute.

The challengers say former state Sen. Russell Pearce has provided a limited set of documents, but contend he has made inadequate searches for all records sought by a subpoena.

An attorney representing Pearce maintains the subpoena was defective and said Pearce's response to the subpoena was more than adequate.

The challengers say they want access to letters, emails and memos between lawmakers and advocates for tougher immigration enforcement to see why proponents of the law believed it needed to be passed.

They are seeking documents to back up their claim that the law was passed with a discriminatory intent.