Making A Murderer should terrify you.

The story of Steven Avery — sent to prison for 18 years for a rape he didn't commit, following an investigation so shoddy you'd be forgiven for thinking sheriff's deputies in Manitowoc County, Wis. railroaded him; then exonerated and released thanks to DNA evidence, before he was again arrested, convicted, and sent to prison two years later, this time for life, following an even more questionable murder investigation — is illuminating and outrageous, and helps explain why the 10-part documentary about his trials became a sensation.

But scarier still than a criminal justice system with investigators who, without lawyers present, can coerce a mentally infirm 15-year-old boy into a false confession — as sheriff's investigators from the same Manitowoc County did with Avery's cousin, Brendan Dassey — is how many more Steve Averys are in the world, and how close the story came to not being told at all.

Through Making A Murderer's 10 parts, rapt binge-watching viewers saw "three or four hours" of Avery's 2007 trial for the murder of Teresa Halbach, a photographer who disappeared after visiting the Avery family's salvage yard — more time spent watching what actually goes on in a courtroom than most Americans will ever spend.

The documentary exploded the myth that "a presumption of innocence really applies" to criminal defendants, says Jerry Buting, one of Avery's two defense lawyers, but also illustrates how little scrutiny is actually given to justice in America.

In Wisconsin, all court proceedings can be recorded. Citizens can watch trials and oral arguments in high-profile cases from their home computers — meaning filmmakers Laura Ricciardi and Moira Demos had access to that vital content.

Had Avery been tried in California, where cameras are allowed in courtrooms only if the judge approves — and where any subsequent recordings are not a public record — and had the excruciating, hours-long interrogation of Brendan Dassey not been recorded by deputies, "nobody would ever have seen this documentary," Buting says.

"People do need to know what goes on in the courtroom — that is probably the biggest single lesson from the documentary," says Buting, who with Dean Strang, Avery's other defense attorney — unlikely international superstars following their ultimately unsuccessful advocacy for Avery in the courtroom — visit San Francisco on Saturday as part of an international criminal justice talking tour.

Since the documentary debuted last December, both Buting and Strang have had their law offices inundated with calls from other defendants who say they have a story like Avery's: questionable evidence, inadequate defense.

"There are cases like this everywhere in the country," Buting says. "People just don't follow it because there aren't cameras in the courtroom."

Proof positive that what happened to Avery and Dassey happens all over the country is found in the agonizing process through which Dassey confesses to the crime — a confession eked out by his own defense team.

Following heavy coaching from deputies and his defense investigator — who appeared to be on the same team — Dassey's confession came on a pre-printed form that had only two options for an accused to choose from: "I'm sorry for what I did," and "I'm not sorry."

"When I saw that pre-printed form, I said, 'That's been used before.' How many others had been subjected to those techniques? We'll never know," Buting tells SF Weekly from his office in Wisconsin. "That's something that really disturbs people."

Making A Murderer has another harsh lesson. The Avery family are the salt of the earth in Manitowoc County, where local society looks down on them as barely-civilized rednecks. It's no secret the criminal justice system feasts on low-income, lower-class people — even in San Francisco, our jails have plenty of homeless people — but the Averys have one advantage. They're white.

"One question we often get asked is, 'Do we think this documentary would have had the same effect if Steven Avery was black?' And, sadly, no — I don't think it would," Buting says. "Too many people would just write that off [with], 'Oh, we've been hearing about that for years.' They could say, 'Oh, that doesn't apply to me.' Therefore, they don't get as offended by it, sadly."

The documentary is also exploding myths around the world, where the American criminal justice system is looked to as a model of how to do things right.

"It's shocking for people elsewhere to see that there are deep-seated flaws in the system that everyone previously seemed to admire," he says. "That's been eye-opening for everyone."

The biggest flaw is the most obvious. America has more people in prison than any other nation per capita. That's well known, but what that means is that much more money is spent on keeping people locked up than on deciding whether or not they should be locked up.

"There are a lot of inadequate defense attorneys out there who are still practicing, because for the better ones, there isn't enough money to make it worthwhile," Buting says. "And quite frankly, the prosecution is underfunded, too. The whole court system has become underfunded because we're spending too much on the corrections part of criminal justice."