"It showed on my tests that I have not been using drugs at all," he noted. "I'm getting arrested for being sober and driving. That's it."
While we'll never know what the officer was really thinking, critics inside the police department point to a pressure on officers to generate numbers -- numbers that police brass can use to brag to the public about all the drunk drivers they've taken off the roads.
A short time before he resigned, former Metro Police Chief Ronal Serpas declared in a news conference, "I'm going to admit for the first time on television there is a quota. The quota is we want to get every drunk driver."
Serpas always insisted there were no arrest quotas.
But NewsChannel 5 Investigates obtained several recent memos in which a DUI lieutenant warned officers that they could face disciplinary action if they did not start arresting more people.
"Self-motivated officers ... should more often than not be able to arrest 2 DUI offenders each 8.5 hour shift," one memo read.
That's "not a quota," the memo claimed, "but simply a benchmark."
But then it added, "If improvement does not take place, additional corrective action will occur."
NewsChannel 5 Investigates had asked Serpas, "You don't see that as a quota?"
"No," the chief answered. "What the lieutenant is saying is that we have an expectation that the only thing you do all day is find DUI offenders and obviously there is some expectation that we should be able to see so many of these on average."
Veteran Nashville lawyer Gary Blackburn disagreed.
"Oh, it's plainly a quota," he said. Blackburn said that setting an expectation of the number of arrests per shift clearly puts pressure on officers every single night.
"If you're trying to average two per night and you are in the last hour of your shift and you have none or you have one, then what is your thought process going to be? Because if you don't make the second one that night, do you have to make three the next?"
Add to that, a financial incentive.
On March 31st, patrol officers who get overtime to chase DUIs were told that the lieutenant "will begin looking at individual officer performance.... Those officers who consistently perform at high standards will be given preference" for the overtime.
Three days later, one of those officers arrested Martin Bills.
Blackburn said such measures make it more likely that officers will arrest people whom they would otherwise let go.
"It's wrong to pressure hard-working, stressed-out officers to make decisions based not on whether they genuinely perceive the motorist as being intoxicated, but on whether they have to meet another quota for that night," he added.
"The result will be inevitably that some innocent persons are going to be affected by this."
One officer who received a warning was Wallace Taylor, who's been repeatedly honored as one of the city's top DUI officers.
But police said that they just don't buy that there are fewer drunk drivers. They said other officers are able to meet the "job performance standard," so every officer should.
Experts added that defense lawyers can use such mandates to attack the credibility of DUI officers in court by suggesting they're just trying to save their own jobs.
Martin Bills' father, Everett, said, "It makes me take another look at the way they do business."
When Bills and his father showed up in court, even though blood tests showed he was clean, the prosecutor told him he'd have to wait at least four months for the charges to be dropped -- unless he pleaded guilty to something else.
He pleaded guilty to speeding -- even though the officer never even charged him with that offense.
"It's gotten out of hand now," Martin Bills said. "So it's just time to end it all now and move on with my life."