Three groups opposed to the expansion of Plant Vogtle have filed a lawsuit in Fulton County Superior court against the Public Service Commission, challenging the decision by state regulators to approve Georgia Power’s new cost estimates for the embattled nuclear plant.

The Southern Environmental Law Center (SELC), Partnership for Southern Equity, and Georgia Interfaith Power and Light argued in their petition that commissioners violated state laws and the commission’s own rules approving spending that would nearly double the estimated costs of the project.

In the petition, SELC said Georgia Power violated the law by communicating behind doors with PSC commissioners days ahead of the controversial December vote.

The SELC argues that the parties involved in the Vogtle hearings were not provided an opportunity to respond to the “substance of the communications.”

The groups are now calling for a review of the final order released by the commission last month, which approved new project costs and schedule.

“The commissioners rushed a decision concerning the single most expensive capital project in state history, giving Georgia Power everything it asked for and sticking customers with all the risk,” said Kurt Ebersbach, senior attorney with the Southern Environmental Law Center.

Consumer advocacy groups have long argued that shareholders’ interests should be considered alongside those of consumers, who are tasked with financing the over-budgeted project.

“The burden of continuing the Vogtle project will fall particularly hard on Georgia’s most vulnerable communities who need real bill relief now,” said Nathaniel Smith, chief equity officer at the Partnership for Southern Equity.

Through a spokesperson, the PSC said they were aware of the filing but had not had a chance to review the lawsuit.

“Because the case is in court now and we are represented by the Attorney General of Georgia, I cannot comment,” said PSC Vice Chairman Tim Echols via email.

Georgia Power, which holds 45.7 percent ownership of Plant Vogtle said through a spokesperson that the “decision by the Georgia PSC to continue the Vogtle project was well within its authority and complied with all applicable laws.”

The latest legal action comes on the heels of an assertion early this month by commissioners that their order on Vogtle should stand. The commissioners unanimously rejected a petition filed by consumer advocacy group, Georgia Watch, which was calling on them to reconsider.

Expansion of the two nuclear units in Waynesboro has elicited opposition from consumer advocacy groups challenging the commission's decision to have ratepayers finance the projects construction costs. Two state lawmakers recently introduced different bills seeking consumer protections to ensure Georgia Power does not profit from the project delays.

The project, in its ninth year of construction, has suffered numerous delays resulting in cost overruns. By Georgia Power’s latest estimates, completion is set for 2022, five years behind schedule .