The legal fight over President Barack Obama's executive order to protect up to 5 million undocumented residents from deportation heated up on Friday as opening arguments in the case were presented before a federal appeals court.

The debate began back in November when the president announced that he would use his executive authority to shield millions of immigrants from being deported. In response, Texas led a coalition of 25 states in filing a lawsuit against the relief programs, arguing that it would hurt their states and violate the Constitution. Subsequently, a Texas district judge issued a temporary injunction in February that stalled the implementation of Obama's plan while the constitutionality of the policy is being considered.

On Friday, a 5th Circuit Court of Appeals panel held a special hearing in the case where two of the three judges grilled lawyers on both sides to the case.

"We are looking at unlawful action which no one could challenge," said Judge, Jennifer Elrod, an appointee of President George W. Bush, suggesting that the DOJ's arguments could be lead to legal protection for every undocumented immigrant to remain in the country, according to the New York Times.

On the other hand, lawyers representing the State of Texas faced sharp questioning from a judge appointed by Obama, who repeatedly suggested that courts should not interfere in matters regarding federal agencies and their authority.

During the more than two-hour hearing, Benjamin Mizer, the Justice Department's principal deputy assistant attorney general, called the lawsuit unprecedented. He also argued that the federal government reserves the right to regulate immigration policy.

"If Texas is right, it could challenge an individual's right to seek asylum," Mizer said, reports CBS News. "The states do not have standing in the downstream effects of a federal immigration policy."

Scott Keller, Texas' solicitor general, argued that Obama's immigration plan will directly hurt Texas because the state will absorb the costs of providing drivers' licenses, schooling and health care to immigrants granted permission to stay in the country.

"This is one of the largest changes in immigration policy in the nation's history," Keller said. "What this is doing is conferring a legal presence" to people now living illegally in the country, he said. "We absolutely have a stake," he added.

Meanwhile, immigrant advocates rallied outside of the courtroom in favor of Obama's policy.

"We are human. We want family to be together," said Victor Ibarra, a 43-year-old protester from Houston. "We just want to be OK in this country, cause no trouble and have the opportunity to be in the U.S. all our life."

The judges did not rule and took the case under advisement.