A judge's decision is expected later this month on a challenge to the change in the industrial-use section of the Town of Westfield zoning ordinance.
The case was heard Friday morning by State Supreme Court Justice Joseph Ricotta.
Several residents have said the Town Board changed the ordinance without a letter from the Chautauqua County Planning Board or an adequate environmental study.
They said the change was made to accommodate the proposed Containerboard factory or other heavy industry.
In other action concerning the project, the county would be willing to be the lead agency for the environmental studies for the proposed plant, a spokesman for County Executive Andrew Goodell said Friday.
Peter Burke of Buffalo, a former regional attorney for the state Department of Environmental Conservation, is a consultant to the county for the project.