Examination of current law revealed the chief constraints to be: the constitutional requirement that searches and seizures be 'reasonable'; state implied-consent legislation; and court decisions that require the retention of breath ampoules. As a result of these constraints: Devices requiring the tested subject's cooperation cannot be used unless there is 'probable cause' to arrest for driving while intoxicated; legislation requiring that an officer arrest a driver before testing precludes the administration of all prearrest tests in most states; implied-consent legislation offers drivers a number of options that could limit the use of certain testing devices in some states; and police officers and prosecutors in a few states must retain breath ampoules for possible further testing. Constraint resolution strategies include: administering active tests only when probable cause exists; amending implied-consent legislation to permit the use of new devices; and appealing adverse court decisions where necessary. (NTIS abstract)