A group of lawmakers whose legislative districts abut the Delaware River in Philadelphia asked the Pennsylvania Supreme Court today to halt construction of the proposed Sugarhouse Casino, contending that its license to build on submerged land beyond the river's edge is illegal.

The lawsuit, which names the city as defendant, attacks the recent decision by the city Commerce Department that granted riparian rights for underwater development to the builders, HSP Gaming.

HSP this year acquired a state license to build on 22 acres along North Delaware Avenue in a decision that has been hotly contested by people opposed to having a casino in their riverfront neighborhoods.

But the subsequently acquired water rights were granted illegally, said Catherine Recker, lawyer for the lawmakers, because the city Commerce Department lacked legal standing to make the decision and, in any case, relied on a 1907 state law that was superseded by another state law in 1978.

"This is about sovereignty" and the power of the legislature to grant riparian rights, which are the rights to the Delaware's river-bottom. "We can't stand by and let the city make an end run" around that power, said Rep. William Keller, who was joined by Reps. John Taylor and Michael O'Brien at a news conference announcing the lawsuit.

"Whether you want to put up a hot dog stand, or relocate the Vatican, there is a process" that must be followed, O'Brien said.

While saying that the motivation for the lawsuit is to defend the legislature's legitimate prerogatives, O'Brien acknowledged in his answer to a reporter's question that the Supreme Court challenge could lead to a reconsideration of the efficacy of the whole Sugarhouse project after Mayor-elect Michael Nutter takes office next month.

According to the lawsuit, submerged land on navigable waters in the commonwealth is owned by the state, and only the legislature has the authority to sell or lease it.

Messages left with the city Commerce Department and with Sugarhouse corporate headquarters were not immediately returned.