A federal appeals court in Virginia has reversed a judge's ruling requiring the nation's largest public utility to promptly install upgraded emission controls at four coal-fired power plants.

Three of the Tennessee Valley Authority plants are in Tennessee, and the other is in Alabama.

U.S. District Judge Lacy Thornburg had ordered the accelerated cleanup at the TVA plants, ruling that emissions affecting air quality in North Carolina's scenic western mountains were a "public nuisance."

A three-judge panel of the 4th U.S. Circuit Court of Appeals in Richmond overturned that ruling Monday. Appeals court Judge J. Harvie Wilkinson III wrote that allowing the ruling to stand would undermine the nation's carefully created regulatory scheme.

Americans' confidence in the economy eroded further in July amid worries about a job market that has proven stubbornly stagnant. The report raised concerns about the overall economy and the back-to-school season.

The Conference Board, a private research group, said Tuesday that its Consumer Confidence Index slipped to 50.4 in July, down from the revised 54.3 in June. Economists surveyed by Thomson Reuters expected 51.0. The decline follows last month's nearly 10-point drop, from 62.7 in May, which marked the biggest since February, when the measure also fell 10 points.

The second straight month of declining confidence follows three months of increases.

With unemployment stuck near 10 percent and the stock market having wiped out gains made early this year, Americans are skittish about spending. A continuing stream of sobering economic data -- from disappointing job figures in May and June to weak housing numbers -- is increasing worries that the economic recovery is stalling just as government stimulus programs are disappearing.

Home prices rose in May for the second straight month as federal tax incentives pulled more buyers into the market.

The Standard & Poor's/Case-Shiller 20-city home price index released Tuesday posted a 1.3 percent increase in May from April.

Nineteen of 20 cities showed price gains month over month. Minneapolis and Atlanta led the way with 2.8 percent and 2 percent increases, respectively. And San Diego posted its 13th straight monthly gain.

Only Las Vegas recorded a price decline. The metro hit a new record low in May. Home prices there have lost 56.4 percent of their value since peaking in August 2006.

And while Detroit recorded a 0.7 percent increase from April, the average home price there is about same as it was in 1994.

Overall, the gains underscore the impact of the government's homebuying tax credits. Buyers rushed to purchase before the credits expired at the end of April. The index is an average of home sales in March, April and May.