"The Class Action Fairness Act of 2005 marks a critical step toward ending the lawsuit culture in our country," Bush said.
Class-action cases allow plaintiffs to combine claims into one suit against a common defendant. Bush has sought to restrain class-action suits as part of his drive to overhaul the civil justice system.
Backers say the changes are needed to stop aggressive trial lawyers from seeking out friendly state courts willing to approve large settlements against out-of-state businesses.
But opponents said overworked federal courts will not take many consumer, environmental and civil rights cases filed under state laws, making it harder for ordinary citizens to hold big companies to account.