The banner of the First Amendment is being waved in another lawsuit, but instead of The Washington Post or the New York Times, the latest company to take up the cause of freedom of expression is the Du Pont Co.

Du Pont has filed suit in federal court in Wilmington charging the Federal Trade Commission with violating the company's First Amendment rights by trying to prevent it from providing customers with advance notice of price changes for lead antiknocks.

Lead antiknocks are used by the oil industry to increase the octane rating of gasoline.

The FTC charged in a May 30 complaint that Du Pont and three other lead antiknock producers were acting illegally by selling that product on a uniform delivered-price basis, giving customers assurances that they would not be charged any more than other customers, giving advance notice of price changes and providing price information to the press.

The companies were not charged with price-fixing or illegal conspiracies.

In response, Du Pont went to court to claim that by trying to prevent it from publishing prices in the press, the FTC was violating the company's First Amendment rights.

"It seems to me that commercial news is news just as much as any news," Du Pont Chairman Irving Shapiro said in a recent interview. "Where the FTC has gone wrong is in suggesting that you can embargo certain people from dealing with the press."

While the FTC would allow Du Pont to tell customers privately about prices, it seeks to prevent the company from announcing them publicly, to the trade press, for example.

"As soon as we go to our first customer and say we are going to raise prices, the entire industry will know within an hour," Shapiro claimed. "It's a silly trap they would be setting up. If the press calls me up, I can't talk to them, but if they call my customer, he can tell them everything."