bruce capsack is a dui defense attorney and teaches offices how to administer field sobriety tests. >> these tests were developed 30 years ago, we're not in the same shape that we were 30 years ago. there has not been any real research as to how regular people perform these. >> reporter: capsack also says the field sobriety test also tells officers whether someone has or does not have alcohol in their system and they don't give a person's ability on whether they can drive a call. the officer can't do the very test he's using on the driver. >> put your arms down on the side i want you to hold it -- >> that's funny, you can't even do it. >> i'm not going to do that test. i'm not going to do that test. >> reporter: officer sam morgan has stopped dozens of suspected drunk drivers in his years as the california highway patrol. >> most people when they are sober can't can pass the test. >> reporter: he says the field tests are very accurate. >> take a deep breath. you blow steadily into the machine. >> reporter: to test the test i blew into a preliminary alcohol screening device what people

bruce capsack is a dui defense attorney and teaches offices how to administer field sobriety tests. >> these tests were developed 30 years ago, we're not in the same shape that we were 30 years ago. there has not been any real research as to how regular people perform these. >> reporter: capsack also says the field sobriety test also tells officers whether someone has or does not have alcohol in their system and they don't give a person's ability on whether they can drive a call. the officer can't do the very test he's using on the driver. >> put your arms down on the side i want you to hold it -- >> that's funny, you can't even do it. >> i'm not going to do that test. i'm not going to do that test. >> reporter: officer sam morgan has stopped dozens of suspected drunk drivers in his years as the california highway patrol. >> most people when they are sober can't can pass the test. >> reporter: he says the field tests are very accurate. >> take a deep breath. you blow steadily into the machine. >> reporter: to test the test i blew into a preliminary alcohol screening device what people