Robert Krieg worked for the Streets and Sanitation Department of Marion, Indiana. In 2002, the city entered into a collective bargaining agreement (CBA) that allowed random and unnotified drug tests for "safety-sensitive"employees. A "safety-sensitive"position was a position that required the employee to hold a commercial driver's license (CDL). Krieg's position required a valid CDL for any new hires, but he was grandfathered in and was not required to obtain a CDL. He still operated pieces of large machinery, such as snowplows and dump trucks, but not commercial vehicles. On October 28, 2004, it was announced that every employee would have to submit to a drug test or face termination of employment. Krieg refused to take the drug test and called his attorney. He was subsequently fired and filed suit against the city, alleging that a forced drug test for non-CDL employees was an illegal search under the Fourth Amendment. The city argued that the union had agreed to the random, unannounced drug testing in its CBA, and also that Krieg was a "safety-sensitive"employee, which allowed the city to require the drug test; based on these contentions, the city moved for summary judgment. The district court granted summary judgment to the city. On appeal, the city's argument that the union had agreed to the drug tests for non-CDL employees was rejected, but the appeals court still affirmed that the city was legally allowed to require a drug test from Krieg. What was the court of appeals' reasoning in allowing Krieg to be randomly tested for drugs? Krieg v. Seybold, 481 F.3d 512 (7th Cir. 2007).