The justices have a few words for securities class-action attorneys: no more frivolous lawsuits.

In a ruling today, the court voted 8 to 1 to endorse stricter standards for the filing of class-action lawsuits by investors. Now, in order to bring such an action, plaintiffs' attorneys must be able to show that the companies or their executives had "cogent" intent to commit securities fraud.

The vote overturns an appeals-court decision in a case involving Tellabs. Investors accused the fiber-optic-equipment maker and its executives of inflating its stock price by issuing false information about key earnings and sales expectations. When the company corrected the reports, in 2001, its stock fell 75 percent from the high it reached at the time those statements were made.

At issue in the court's decision was the interpretation of a provision in the Private Securities Litigation Reform Act of 1995, which requires investors to show a "strong inference" that a company or its executives intended to defraud them.

Today's ruling is an important victory for public companies, because it means a suit that doesn't meet legal standards can be thrown out before the discovery process begins.

Earlier this year, the Securities and Exchange Commission and the Department of Justice had filed a brief in favor of adopting higher standards for securities-related lawsuits.

This is the second Supreme Court ruling in recent weeks of particular significance for investors. Last week, the court ruled that Wall Street firms under investigation for pricing practices relating to initial public offerings during the dotcom era cannot be sued under antitrust laws.

Justice Ginsburg authored the court's opinion today. The lone dissenter was Justice Stevens.