AUSTIN (CBSDFW.COM) – The Texas Supreme Court heard arguments Thursday in a class action lawsuit challenging whether red-light cameras are constitutional.

Residents of the small Texas town of Willis are suing their city, saying the cameras are illegal, in part, because a state-required engineering study was not done before the cameras were installed.

The suit seeks more than $1 million in reimbursement for the red-light camera tickets issued.

The CBS 11 I-Team reported last week on how a dozen north Texas cities also did not do an engineering study before putting up the cameras.

The North Texas cities told the I-Team they believe they are grandfathered into the law requiring the study.

Senate Bill 1119, passed in 2007, required cities to conduct an engineering study to justify the cameras’ use. Lawmakers wanted to make sure red-light cameras were installed for safety reasons and not as a revenue generator.

State Representative Jim Murphy, who co-authored SB 1119, said no city was grandfathered into the study requirement.

The Texas Supreme Court is expected to issue an opinion on the Willis case in the next two to three months.

In September, Gov. Greg Abbott called to ban red-light cameras in Texas.