ST. LOUIS • Standing in front of the building where slave Dred Scott sued to gain his freedom, Gov. Jay Nixon vetoed a measure that would have made it easier for employers to avoid discrimination suits.

The bill would have raised the threshold for proving bias cases, requiring claimants to prove discrimination was a "motivating" factor, and not just a "contributing" factor, which is the current standard.

It would also have capped damages awarded to plaintiffs, and exempted individuals — such as a boss or supervisor — from liability.

"Protecting human rights is not a matter of politics," Nixon said. "It is a matter of principle. That is why I will veto Senate Bill 188."

Standing in front of the Old Courthouse, Nixon evoked the names of prominent local civil rights leaders such Minnie Liddell, the St. Louis mother who started a marathon desegregation case that was the source of much political consternation for Nixon when he was attorney general.

Surrounded by members of groups representing minorities and the disabled, he urged them to "lock arms" to help ensure his veto is not overturned in the waning days of the legislative session.

While the governor has shown a willingness to work with the GOP on key issues — most notably the compromise on dog breeders — Nixon signaled he would not be amenable to a compromise that would not budge on laws relating to discrimination in the workplace. 

"We will not cede one inch of ground it has taken us decades to gain," Nixon said.

Changing employment discrimination laws was part of a package of proposals dubbed "Fix the Six" by the state Chamber of Commerce. 

Nixon has said that he's open to working with the chamber — earlier this week he repealed the corporate franchise tax, a measure the group had sought — but suggested that discrimination laws were not on the table.

"We're not going to boost the economy by going backwards on individual rights," Nixon said.