If Republican Gov. Phil Bryant signs the bill, it will become law July 1. The measure is pushed by the Mississippi Manufacturers Association and other business groups.
The bill passed the House 63-56 and the Senate 31-15.
Supporters, including Rep. Mark Formby, R-Picayune, said the bill is a way to bring balance to a system that has long-favored injured workers. He said the changes might reduce employers' premiums for workers compensation insurance.
"To me, it's a lot more about fairness than it is about payments," Formby said.
Opponents said the changes would make it difficult for people who are hurt on the job, or for survivors of those who are killed, to receive compensation.
"What this legislation boils down to is a direct assault on the working class people in the state of Mississippi," said Rep. Bryant Clark, D-Pickens. "If this bill becomes law, what it's going to do is place burdens on our workers that no other state in the union places on theirs."
Among other things, the bill says no compensation would be owed to a worker who is found to be under the influence of alcohol or drugs, including the improper use of legal prescription drugs, when an on-the-job injury occurs. Current law does not specifically mention drugs or alcohol but says no compensation is owed to the worker "if the intoxication of the employee was the proximate cause of the injury."
Sen. Derrick Simmons, D-Greenville, said testing for prescription drugs or other drugs "may be worse for workers."
Sen. Longwitz, R-Madison, who supported the bill, said the provisions are designed to make work places safer. He also said the bill will allow employers to test workers "without being worried about being dragged into court."
The bill also sets a 60-day deadline for a worker who is hurt on the job to file medical records that support his claim for compensation. Current law doesn't mention a deadline.
It also would allow a partial reduction in payments to any worker who is injured on the job but had pre-existing conditions such as a bad back.
Opponents of the bill said employers have long benefited from the workers compensation system because it allows a three-person administrative commission to make decisions about workers' claims, keeping some of the claims from becoming protracted lawsuits.