No Way Out

the voting register as well as census data.”

“Wait a minute, you have to be careful how you handle the data. The voting register excludes people incarcerated for felony convictions, but those serving time for misdemeanors can still vote. However, they can’t serve on juries.”

Andi folded her arms and pursed her teeth.

“Please give me credit for a modicum of common sense. I held constant for all incarcerations, including pre-trial detention. The pattern still holds.”

“Pattern?”

“I don’t mean the size of the imbalance stayed constant. Obviously it was reduced when I held constant for those variables. But a statistically significant discrepancy remained.”

“Meaning in plain English that it was too big to be a — ”

“Random deviation? Exactly.”

“Okay but you base that on the assumption that the use of driver’s license records would be sufficient to plug the gap left by under-representation of blacks on the voting register. But not everybody drives. Some people use the bus.”

“The DMV also issues non-driver IDs.”

“But only to those who request them.”

“Come off it! There isn’t an eighteen-year-old in the State who doesn’t want to buy smokes or booze. And once they’ve got the ID, they’re registered at the DMV. And that makes them eligible for jury service.

Alex shook his head, not to argue but merely as he struggled to take it all in.

“Okay, hold on a minute, let’s rewind. First of all how are juries chosen?”

“We’ve been through that over and over: from voting registers and car license records. I think they use property tax records too.”

“No what I mean is, once they’ve got the records how do they make the actual selection?”

“Well nowadays it’s done by computer.”

“And how does the computer actually do it?”

“What do you mean?”

“I mean, according to what criteria does the computer make its decision?”

“It’s random! That’s the whole idea!”

“Yes,” Alex persisted, “but how does something as deterministic as a computer make a random decision?”

He was remembering a discussion with David not long ago. David had tried to explain to him about “pseudo- random behavior in deterministic systems.” Of course David’s area of interest was cosmology and sub-atomic particles. But the discussion had fascinated Alex, even if he hadn’t entirely understood what David had painstakingly set out to explain to him.

“Okay let’s say the Court needs 200 prospective jurors for that week,” Andi began. “And there are a 50,000 eligible people in the district or county. The computer divides a 50,000 by 200 and gets 250. That means they need to summon one person for every 250 in the district. So the computer chooses every 250^th name on the list.”

“That’s it?”

“Well no, not quite. If the computer just did that, then it would always choose the first person on the list and then all the other people at fixed intervals. So instead, what the computer does is it creates what’s called a ‘random offset.’”

“Random offset?” Alex repeated.

“Yes. What that means is that it picks a random number between one and 249. Then it counts that number in and picks that person as the first juror. So let’s say it picks the random number 187 as the random offset. What it does then is pick the 187^th person on the list as its first selection and then pick every 250^th person thereafter, until it gets to the end of the list.”

“Okay,” said Alex. “But how does a computer choose a random number in the first place? I mean isn’t everything in a computer mathematical and deterministic.”

He was remembering things that his son had told him.

“It uses something called keyboard latency.”

Alex was looking at her blankly.

“That means the speed at which the person at the keyboard types. What the software does is get the computer operator to type on the keyboard at random. It ignores what keys they press, because that might not be random, but it measures the time between keystrokes — or rather the differences in microseconds between one keystroke and another.”

“Okay.”

“But it doesn’t take the whole figure, it takes what it calls the least significant bit. That means like the last digit on the list of microseconds — that’s millionths of a second. Then the program uses this random input as the seed or initialization vector for the randomization algorithm that calculates a number between — in this case — one and two hundred and fifty.”

Andi paused to catch her breath. Alex paused to take it all in.

“But none of this explains why blacks are under-represented in this case,” said Alex.

“That’s exactly my point. If the software does its job properly, then they shouldn’t be. But all the stats I’ve looked at show that they are. That means that something’s going wrong.”

“But what?”

“I don’t know. But the judge did say causal evidence or statistical evidence. This is clear statistical evidence!”

“I don’t think we have enough to take it before the judge.”

“Why not?”

“Because if she rejected it once then she’ll reject it again.”

“But it’s different now! Then it was just one panel. Now it’s across the state for the last five years.”

“That’s going to make it even harder.”

Andi was surprised at this.

“Why?”

“Because if you tell her this, then any decision she makes will have implications for thousands of other cases, not just this one. And I don’t think she’s going to want that sort of responsibility. She’d rather leave it to the Court of Appeal instead of taking it on her own head.”

“So what are we going to do? Just drop it and walk away like we haven’t discovered anything?”

“No but we’re going to need to bolster our arguments.”

“How?”

“By finding some causal explanation for these stats.”

“And how are we going to do that?”

“That’s what I was hoping you could tell me.”

Andi thought about this for a moment.

“Maybe if we could find some glitch in the software.”

“Do you have the skill for that?”

“Probably not. I mean I actually tried to learn programming in C++, but I kind of… dropped out of the course.”

Alex pursed his lips.

“If it is a software glitch, I think I may know some one who can help.”

“Who?”

“My son, David. He’s a physicist at Berkeley. Get his number from Juanita and call him. Tell him you’re working for me.”

“For you?”