Abstract
The presence of chronic respiratory disease is sometimes claimed as a defence by drivers who refuse or fail a breath test. Trials were conducted with two instruments used in Victoria in order to determine the effort required for a satisfactory test. Patients with restrictive and obstructive conditions participated in the trial which was conducted at the respiratory unit of a large hospital. The results are presented. They provide information useful in refuting defenses of inability to provide a breath sample due to respiratory incapacity. (A)