U.S. District Court Judge Thomas F. hogan dismissed as premature yesterday a suit contending that the Federal Trade Commission and other independent regulatory agencies have no constitutional power to enforce laws because they are not fully part of the government's executive branch.

The novel constitutional challenge was filed by Ticor Title Insurance Co. and five other title insurance firms that have been charge by the FTC with price-fixing. The suit was argued for them last month by Theodore B. Lson, who was an assistant attorney general in President Reagan's firswt term.

"The constitutionality of independent fderal agencies has never been fully adjudicated," Hogan wrote in an 11-page opinion. "The issue has been avoided for years." But he said he concluded "reluctantly" that under a recent ruling by the U.S. Court of Appeals for the District of Columbia, he cannot decide the issue now because the FTC has not made a final decision in the price-fixing case. It is scheduled for a hearing before an administrative law judge next month.

Olson had argued for Ticor that, while the president nominates FTC commissioners, he cannot fire them except for cause. Therefore, he said, the agency is not under the supervisory control of the president, who has sole power to enforce the law under the Constitution.

Olson could not be reached last night for comment on whether Hogan's ruling will be appealed.