The Supreme Court has decided not to hear a truck driver’s appeal against a lower-court decision that found a motor carrier had the right to screen certain drivers for obstructive sleep apnea.

In October, 2013, the Eight Circuit Court of Appeals ruled against Robert Parker, who had sued Crete Carrier Corp. back in 2013 on the grounds that its apnea-screening protocol violated the Americans with Disabilities Act. Parker had sought reinstatement and back pay, having been fired by Crete for refusing to be tested for the medical condition.

In its April 3 order list, the Supreme Court denied Parker’s petition to review the lower court’s ruling. The court is usually not under any obligation to hear such cases. Typically, it only does so if a case could have national significance, might harmonize conflicting decisions in the federal circuit courts, and/or have precedential value. The upshot is the court only hears 100 to150 of the over 7,000 cases that it is petitioned to review each year

By letting the Eight Circuit’s ruling stand, the Supreme Court in effect sets a precedent for other lower courts to consider in ruling on such cases going forward.

That suggests motor carriers may consider putting in place similar apnea-screening programs with less fear of lawsuits being brought successfully against them by drivers seeking to avoid such testing.

Testing drivers for obstructive sleep apnea remains the purview of individual employers as the Federal Motor Carrier Safety Administration has yet to issue any rule requiring carriers to screen drivers for the condition.

And while the Trump administration generally favors reducing regulations, an apnea rule would be welcome by many truck fleet operators as well as by highway safety advocates.

But fleets should not hold their breath: It was more than a year ago that federal regulators got only so far as to issue a “pre rule” on sleep apnea for transportation workers.

FMCSA and the Federal Railroad Administration jointly announced on March 8, 2016  an Advance Notice of Proposed Rulemaking that they said would serve as “the first step” in considering whether to propose specific requirements around obstructive sleep apnea.

Related: How Not to Lose Sleep over Apnea