It has commonly been assumed that a urine test for marijuana use can yield a positive result for a week or longer. Recent research showed that, when the Federal Government's cutoff level for a positive test is used, the time period for detection after use, the window of detection, can be less than 2 days for an individual who smoked one marijuana cigarette. Researchers tested more than 1,000 urine specimens from six male subjects over a three-week period. A computer was used to standardize the number of puffs each subject took on a marijuana cigarette, time between puffs, the amount of time the smoke was inhaled, and the amount of time it was held in; there was no control for the depth of inhalation. Each subject had specimens tested on seven different immunoassays at different cutoff levels. Results were also obtained from tests on the gas chromatography/mass spectrometry drug testing system.