Mary Teresa Slaney (formerly Tabb, née Decker, born August 4, 1958) is an American retired middle-distance and long-distance runner.

Unable to attend the 1972 Olympics as she was too young at 14, Decker, who ran wearing pigtails and at the weight of 89 lb (40 kg), won international acclaim in 1973 with a win in the 800 meters at a U.S.-USSR meet in Minsk, beating the reigning Olympic silver medalist Nijolė Sabaitė.

This resulted in a series of injuries that prevented her from competing in the 1976 Summer Olympics because of stress fractures in her lower leg.

[citation needed] After recovering from surgery, she spent two seasons at the University of Colorado at Boulder on a track scholarship.

[8] In 1982, under the name Mary Tabb, she ran the mile in 4:18.08, breaking the official record of 4:20.89 by the Lyudmila Veselkova of the USSR, and this time was ratified.

Her history of relatively easy wins in the United States left her tactical abilities suspect in Helsinki, as she chose not to run in close order because so few athletes could keep up with her, a situation that the Soviet runners hoped to use to their advantage.

After her double win she won the Jesse Owens Award from USA Track and Field and Sports Illustrated magazine named her Sportsperson of the Year.

Decker was heavily favored to win a gold medal in the 3000 meters run at the 1984 Summer Olympics in Los Angeles.

In the final, barefoot runner Zola Budd, representing Great Britain, had been running even with Decker for three laps and then moved ahead.

Decker was carried from the track in tears by her boyfriend (and later husband), British discus thrower Richard Slaney.

[10] Decker and Budd next met in July 1985 for a 3000-meter race at Crystal Palace National Sports Centre in London.

Decker later claimed that she was robbed of the 1984 Olympics 3000-meter gold medal by Budd, but many years after the event said: "The reason I fell, some people think she tripped me deliberately.

In April 1999, the arbitration panel ruled against Decker, and although she was cleared to compete, the IAAF instituted a retroactive ban of two years from June 17, 1996 that stripped her of the silver medal that she had won in the 1500-meter race at the 1997 World Indoor Championships.

After the loss of her 1999 legal case, she underwent more than 30 orthopedic procedures, mainly on her legs and feet, in an attempt to enable her to run competitively in marathons.