Republican senators prodded Homeland Security Secretary Janet Napolitano today to explain how she would implement the pending immigration bill, which gives her numerous powers to tighten or loosen many aspects of immigration law.

“This bill gives you, the secretary, extraordinary discretion in making many decisions about how the [task] would be carried out … that causes me many concerns,” Alabama Republican Sen. Jeff Sessions told Napolitano.

“You’ll have discretion on how much fencing [to build on the U.S.-Mexican border], and the ability to say when it is ‘substantially’ complete,” added Utah Republican Sen. Mike Lee.

“The bill would put no pressure on a [future DHS] secretary to secure the border,” said Iowa Republican Sen. Chuck Grassley.

Both Lee and Grassley said the bill gives the secretary great authority by including 400 waivers and exemptions for her to use when desired.

The hearing was the third to investigate the details of the new 844-page immigration bill.

The complex bill would change many aspects of immigration law, provide conditional legalization to at least 11 million illegal immigrants, and greatly increase today’s annual inflow of one million permanent immigrants and employer-sponsored agricultural, blue-collar and white-collar workers.

Democrats hope to have the bill approved by the Senate in June.

Napolitano did not challenge the GOP’s criticism of the law’s waivers, but she downplayed several waivers that boost her role in deciding how the law is implemented.

She was quizzed about a waiver that allows the secretary to grant work permits to former illegal immigrants who had already been deported, or to illegal immigrants who had committed several crimes in the United States.

“I could see there would be considerations based on the age of a conviction, the type of conviction, whether the individual was the primary wage-earner for the family … the record since the conviction,” she said.

When quizzed about completing the fence on the U.S.-Mexican border, she said the department would prefer to rely on drone aircraft and high-tech surveillance.

“We would prefer money… if we have our druthers, we would not so designate a fence fund,” she said.

The pending bill requires the secretary to develop a plan that would stop 90 percent of border-crosses at three out of nine regions on the border. That’s down from today’s legal requirement of 100 percent stop-rate.

Texas Republican Sen. John Cornyn pressed Napolitano to explain how she would calculate the number of attempted border crossings. Without that initial number, officials cannot know if the patrol is meeting the 90 percent goal, he pointed out.

“That is an inherent problem,” Napolitano admitted.

However, agency officials will use a variety of measure to gauge the total number of border-crosses, she said.

Texas Republican Sen. Ted Cruz slammed Napolitano’s refusal to provide a simple measure of the effectiveness of border-security measures.

“If there are no metrics, how can we have any confidence that the border will be secure?” Cruz asked.

If there is only an “amorphous, multi-factored subjective test, this committee knows to a metaphysical certainty that security will be [declared by the agency to be] satisfied,” he said to Napolitano.

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