Defense attorney Oscar Michelen is no stranger to this fight. Having spent decades exonerating wrongfully convicted individuals, he knows firsthand that the legal system is built to uphold convictions, not revisit them.

Michelen explained how post-conviction cases operate under entirely different rules than initial trials. Once a jury has rendered a verdict, the presumption of innocence disappears, and the burden of proof shifts entirely to the defendant. In most states, a convicted individual cannot simply request DNA testing—they must convince a judge that the evidence will prove their innocence. "Judges don’t want to reopen cases," Michelen said bluntly. "The system values finality over fairness."

He outlined several key obstacles that make post-conviction relief so difficult.

While every state has some provision for post-conviction DNA testing, the laws vary dramatically. Some states require proof that DNA testing will definitely exonerate the individual—a nearly impossible standard, since lawyers cannot predict results before testing occurs. Others set arbitrary deadlines, allowing requests only within a few years of the conviction, which often expires long before DNA advancements make testing feasible. "In many states, you have to prove your innocence before you get access to the very evidence that could prove your innocence," Michelen said. "It’s a Catch-22."

One of the most devastating hurdles is that biological evidence is frequently lost or destroyed. Many crime labs and police departments discard evidence once a conviction is secured, especially in cases before DNA testing was standard practice. Without preserved evidence, exoneration through DNA becomes impossible. "In some cases, we’ve had to search old warehouses, evidence lockers, and even coroner’s offices to find samples that should have been retained," Michelen explained. "And sometimes, we find out it was thrown out long ago."

Even when DNA evidence exists, district attorneys often fight against testing. Prosecutors may argue that a conviction was already upheld on appeal, or that new testing is unnecessary because of other evidence. Some worry about the implications of reopening old cases—admitting mistakes in one case could call into question their entire record. "Innocence shouldn’t be a partisan issue, but too often, it is," Michelen said. "There’s a fear that admitting to one mistake will open the floodgates for hundreds of others."

Even when all legal hurdles are overcome, the financial burden of post-conviction DNA testing is often placed on the defendant or their legal team. Many exonerees spend years in prison because they simply cannot afford the testing that would prove their innocence. "This isn’t just about science," Michelen concluded. "It’s about power, resources, and whether we truly believe in justice."

The fight for justice is not just legal—it’s deeply personal. No one knows this better than David McCallum, who was wrongfully convicted of murder at the age of 16 and spent 29 years in prison before being exonerated.

His case was based solely on a confession he made after hours of police interrogation. There was no physical evidence linking him to the crime, yet he was sentenced to life in prison.

In the webinar, McCallum shared his emotional journey—from the moment he realized he had been convicted to the decades he spent behind bars fighting to prove his innocence.

McCallum was just a teenager when he and his friend Willie Stuckey were arrested for the 1985 abduction and murder of Nathan Blenner. The two boys, overwhelmed by relentless police questioning, falsely confessed to the crime, believing that they would be allowed to go home if they cooperated.

But once their confessions were on record, there was no going back. Despite immediately recanting, both were convicted and sentenced to 25 years to life.

"It’s impossible to explain what it feels like to hear that guilty verdict when you know you’re innocent," McCallum said. "You want to scream, but no one will listen."

McCallum’s journey to freedom was not one he walked alone. A chance connection with Ray Klonsky and his father, Ken Klonsky, would set off a chain of events that ultimately led to his exoneration. The two formed a deep friendship with McCallum, with Ray initially reaching out in 2006 as a filmmaker but quickly becoming a tireless advocate for his release. "Ray was like a brother to me," McCallum shared. "He didn’t just want to tell my story—he wanted to help me get home"

Their fight was strengthened by none other than Rubin “Hurricane” Carter, the former middleweight boxer who had spent nearly 20 years wrongfully incarcerated before his own exoneration. Carter, who dedicated his life to freeing the innocent, saw McCallum’s case as his final mission before passing away in 2014. "He told me, ‘You will walk out of prison one day, and I want to see it happen before I die,’" McCallum recalled. "His belief in me gave me strength."

Carter’s advocacy, along with relentless legal efforts and the media attention from Fight for Justice: David & Me, ultimately pushed the Brooklyn District Attorney’s Conviction Review Unit to reinvestigate the case.

On October 15, 2014, McCallum was finally exonerated.

"I walked out, but Willie Stuckey should have been there too," McCallum said, referring to his childhood friend and co-defendant, who died in prison in 2001. "This isn’t just about me. It’s about everyone still fighting for their freedom."

Lisa Mertz and Krista Currie, both forensic DNA experts, detailed the role of forensic science in post-conviction cases. While DNA has exonerated hundreds of individuals, the process of testing decades-old evidence is far from straightforward.

Mertz and Currie outlined the key forensic challenges:

Before any testing can begin, forensic teams must locate the original evidence. This process can take months, as records are often incomplete or missing entirely. In some cases, the only remaining DNA sample may be a degraded bloodstain or a single hair. "You have to reconstruct the history of the evidence—where it was stored, how it was handled, whether it was tested before," Mertz explained. "Every step in that chain of custody matters."

Older evidence is often stored in less-than-ideal conditions, making contamination a major concern. Forensic scientists must carefully distinguish between the original DNA and any external contaminants that may have been introduced over the years. "When we’re dealing with evidence from 20, 30, even 40 years ago, contamination is always a factor," Currie said. "We have to be meticulous in our analysis."

DNA testing methods have advanced significantly since the 1990s. Where early techniques required large, intact samples, modern methods—such as next-generation sequencing and forensic genetic genealogy—can extract DNA from degraded or trace samples. "We can now analyze evidence that would have been considered useless 10 years ago," Mertz noted. "That’s a game-changer for post-conviction cases."