People wait in line to attend the fall session of the Supreme Court, on Oct. 2, 2017, in Washington. (Mark Wilson/Getty Images)

The Trump administration told the Supreme Court on Thursday that there is no reason for the court to rule on the legality of the president's previous ban on travel from certain countries and that lower-court rulings against the president's position should be erased.

Opponents of the ban, who had persuaded two appeals courts to block the executive order, said the court should continue to review the cases. Even if not, they said, the lower-court rulings should stand.

The justices asked for the new briefing about whether the issue was moot since President Trump announced a replacement travel ban last month. The court canceled an oral argument on the issue scheduled for next week.

The cases raise complicated and far-reaching issues about the president's powers, and many legal experts believe the court may not want to jump in unless it is necessary. It is unclear when the court will rule on whether to proceed.

Solicitor General Noel J. Francisco said the new proclamation means that temporary measures under review at the Supreme Court have been superseded.

"If this court were to continue to hear these appeals, it would be asked to decide questions with no ongoing practical import," Francisco wrote.

He also said two rulings that went against Trump — by a panel of the U.S. Court of Appeals for the 9th Circuit and the U.S. Court of Appeals for the 4th Circuit — should be vacated.

"If allowed to stand, the lower courts' decisions threaten to undermine the executive's ability to deal with sensitive foreign-policy issues in strategically important regions of the world," Francisco wrote.

The previous order was challenged by the state of Hawaii and the American Civil Liberties Union as an illegal ban on Muslims. Hawaii and the ACLU were representing those with family members affected by the ban.

"The 90-day ban on their relatives has now been converted into an indefinite ban with the potential to separate their families, and thousands of others', for years," wrote ACLU lawyer Omar C. Jadwat, asking the court to keep the cases alive.

"And the religious condemnation of the earlier Executive Order is not dissipated by [the new one], which — despite some new window dressing — continues to relay a message of disparagement to the plaintiffs and other members of their faith."

But both the ACLU's submission and the one from Hawaii seemed to acknowledge the possibility that the court would pass on reviewing the old executive orders.

"The court will soon have another opportunity to determine the legality of the President's actions in the context of the new order" because legal challenges to it are underway, wrote Washington attorney Neal K. Katyal, representing Hawaii.

A federal judge in Maryland said this week that those suing over the previous travel ban could amend their complaint and file a request for a preliminary injunction to block the new one. A hearing in the case is scheduled for Oct. 17.

But both challengers said it would be unfair to wipe out lower court decisions because of the government's actions.

"Any mootness would be entirely the consequence of the government's voluntary actions — in managing the timing of the bans, in declining to seek a swift hearing on the merits, and in rebottling its old ban in a new order," Katyal wrote.

"It would be profoundly inequitable to permit the government to use these maneuvers to obtain the very relief it sought on the merits: vacatur of the injunctions," he wrote.

The latest travel ban could block the issuance of tens of thousands of visas each year to people who want to immigrate to the United States or to come on business or as tourists, according to a Washington Post review of State Department data.

In some ways it is more expansive than the second executive order it replaced — remaining in effect indefinitely and imposing restrictions on eight, rather than six, countries. But unlike the previous ban, the restrictions vary from place to place, and countries that increase their cooperation and information-sharing with the United States might be able to find their way off the list.

The proclamation was issued after a lengthy process in which U.S. officials reviewed vetting procedures and sought information from countries around the world. Those that were either unwilling or unable to produce the data the United States wanted ended up on the banned list.

For Syria and North Korea, the president's proclamation blocks immigrants wanting to relocate to the United States and nonimmigrants wishing to visit in some capacity. For Iran, the proclamation blocks both immigrants and nonimmigrants, although it exempts students and those participating in a cultural exchange.

The proclamation blocks people from Chad, Libya and Yemen from coming to the United States as immigrants or on business or tourist visas, and it blocks people from Somalia from coming as immigrants. It names Venezuela, but it blocks only certain government officials and their families. Sudan, which was covered by the previous ban, was removed from the list.

Matt Zapotosky contributed to this report.