WASHINGTON — A federal appeals court on Friday invalidated campaign finance rules that give wealthy donors broad latitude in underwriting expensive political ads.

Limits on coordinated campaign spending apply too narrowly to time frames just before elections and should be toughened, the U.S. Court of Appeals for the District of Columbia Circuit said in the decision.

Judge David Tatel said in the ruling that interest groups often engage in early advertising, in some cases more than a year before an election.

The restrictions the Federal Election Commission imposed apply only to spending within 90 days of a congressional election and 120 days before a presidential primary.

Tatel said the FEC rule frustrates the purpose of the campaign finance reform law enacted in 2002.

The law was designed to halt issue ads purportedly aimed at influencing voters' policy views but actually directed at swaying their views of the candidates.

The issue ads often are underwritten with six-figure political contributions referred to as soft money, which the law was aimed at getting rid of.

"By allowing soft money a continuing role in the form of coordinated expenditures, the FEC's proposed rule would lead to the exact perception and possibility of corruption Congress sought to stamp out," Tatel said.

Under the FEC rule, issue ads outside the 90/120-day time frame mentioning candidates are allowed as long as the ads do not engage in "express advocacy."

The appeals court called the express advocacy requirement a "functionally meaningless" standard. It thwarts the congressional goal of prohibiting soft money from being used in federal elections, Tatel wrote.

The judge added that outside the 90/120-day windows, the regulation allows candidates to evade the soft money restrictions "almost completely."

The appeals court also rejected an FEC rule that permits federal officeholders and candidates to solicit soft money at state party fundraising events. The appeals court said the reform law "directly prohibits" such conduct.

Rep. Christopher Shays, R-Conn., brought the case challenging the FEC rules as contrary to the reform law.

Fred Wertheimer, president of the campaign finance reform group Democracy 21, called the decision "yet another sharp repudiation of the FEC's continued failure to properly implement" the Bipartisan Campaign Reform Act. There have been four court decisions against the FEC rules since 2002.

Tatel is an appointee of former President Clinton. The other judges on the case were Judge Merrick Garland, a Clinton appointee, and Judge Thomas Griffith, an appointee of President Bush.