PIERRE, S.D. (AP) — Opponents of the Keystone XL pipeline have asked a South Dakota judge to reverse state regulators’ decision last year to again authorize the portion of the project that would go through the state.

The decision by the South Dakota Public Utilities Commission’s was appealed to state court, which heard arguments Wednesday in the case. It’s not clear when Judge John Brown will rule.

The commission voted last year to accept the company’s guarantee that it can complete the project while meeting the conditions of the 2010 approval.

The project has prompted opposition from Native American tribes, some landowners and environmental groups concerned the pipeline would contaminate water supplies and contribute to pollution.

Attorneys for TransCanada and the Public Utilities Commission have asked the judge to uphold the order.