The U.S. Supreme Court heard arguments in an appeal by Penn East Pipeline Company LLC, on Wednesday, vying to seize land owned by New Jersey to build a $1 billion natural gas pipeline, according to Reuters.

Opposing the joint venture backed by a group of energy companies, the state argues its rights would be trampled.

The focus of the issue in the case is a 1938 U.S. law called the Natural Gas Act that lets private energy companies seize “necessary” parcels of land for a project if they have obtained a certificate from the Federal Energy Regulatory Commission. The law effectively gives private companies the power of eminent domain.

A ruling in favor of New Jersey would weaken the Natural Gas Act. And while some justices appeared sympathetic to the state’s legal arguments, they also seemed cautious about issuing a ruling that would overturn the longstanding understanding of the law and potentially imperil the PennEast project and others like it.

Learn more: Reuters > U.S. Supreme Court tackles pipeline company’s bid to seize New Jersey land