WASHINGTON (CNN) -- U.S. District Judge Gladys Kessler ruled Thursday that the tobacco industry engaged in racketeering, finding in favor of the government in its lawsuit against the tobacco industry in a 1,653-page ruling.

Kessler said the tobacco companies had engaged in a decades-long conspiracy to hide the dangers of smoking, and ordered them to take out newspaper ads detailing smoking's health effects. The companies were also ordered to stop using such descriptors as "low tar," "light," ultra light," "mild" or "natural" that might imply it is not dangerous.

"We are pleased with the court's finding of liability on the part of the defendants, but disappointed that the court did not impose all of the remedies sought by the government," the Justice Department said in a written statement. "Nevertheless, we are hopeful that the remedies that were imposed by the court can have a significant, positive impact on the health of the American public."

"We're obviously very pleased with the reports of the ruling," said Ed Sweda, of the Tobacco Products Liability Project, an anti-tobacco group based at Northeastern University School of Law in Boston.

"We'll be going through it with great interest."

Kessler found the conspiracy dates back to 1953, when a group of tobacco companies met together at the Plaza Hotel in New York City and devised a public relations plan to counter health concerns associated with smoking.

Kessler said that, even after the 1964 Surgeon General's report linking smoking to lung cancer, tobacco companies continued "to falsely deny and distort the serious health effects of smoking."

As late as last year, she wrote, the defendants still did "not admit the serious effects of smoking which they recognized internally decades ago."

Citing internal industry documents, Kessler said the industry knew that nicotine is addictive, but publicly denied it "and continue to do so."

In addition, she said, the defendants "concealed and suppressed research data and other evidence that nicotine is addictive."

She added that the companies "have falsely denied that they can and do control the level of nicotine delivered in order to create and sustain addiction" and worked on ensuing that "all cigarettes delivered doses of nicotine adequate to create and sustain addiction."

They did so, she wrote, by altering the chemical form of nicotine delivered in smoke and by changing cigarette filters' design and paper porosity and composition.

Kessler added that the government "has failed to prove by a preponderance of the evidence that defendants deliberately chose not to utilize or market feasible designs or product features that could produce less hazardous cigarettes."

She did fault the industry, however, for marketing to youth, concluding that "independent studies have found that marketing is a substantial contributing factor to youth smoking initiation."

Thought the industry has said that it does not want children to smoke, Kessler said the companies tracked youth behavior and preferences, thereby ensuring that "marketing and promotion reaches youth."

In addition, she said, the companies still use marketing themes intended to resonate among youths, advertise in youth-oriented publications and continue price promotions that lure them in.

The companies smoking prevention programs "are not designed to effectively prevent youth smoking," she said.

Kessler also faulted the industry for denying publicly that second-hand smoke is dangerous, citing internal acknowledgments that that is the case.

The case dates back to 1999, when the Justice Department under the Clinton administration accused the tobacco industry of racketeering as part of a coordinated plan to deceive the public about the negative health effects of smoking.

The Bush administration continued to press the charges in the lawsuit, but rolled back the proposed remedies and punishment for the alleged activity.

The industry is on record as denying wrongdoing, and asserting their marketing has changed to further preclude any chance of wrongdoing.