RADLEY BALKO is an award-winning investigative reporter who focuses on civil liberties and criminal justice. He is a senior editor at Reason magazine, where he writes a monthly column. He also writes a weekly column for Reason's website and blogs at Hit & Run and The Agitator , his personal blog, which is a must-read for anyone with a healthy scepticism of the government's activities. Mr Balko's writings have been cited by the US Supreme Court and the Mississippi State Supreme Court, and his reporting has helped illuminate the path to justice in a number of criminal cases—his reporting has even helped get a man off of death row. This week we asked him some questions about the flaws in America's criminal-justice system and the frustrations of being a libertarian.

DIA: You've written about the creeping militarisation of law enforcement in America. How has this trend manifested itself and what are the consequences for the quality of policing?

Mr Balko: The most obvious way it has manifested itself is in the explosion in the use of SWAT teams and similar paramilitary police units over the last 25 years. The criminologist Peter Kraska has surveyed their use over that time. He's found that the total number of SWAT-team deployments in the 1970s was a few hundred times per year, over the entire country. By the 1980s, it was a few thousand times per year. And by around 2005, Mr Kraska estimates around 50,000 times per year. The surge has been driven entirely by the drug war, with the vast majority of SWAT deployments being used to serve drug-related search warrants.

This has led to a militaristic mindset among America's police departments, beyond just SWAT teams. Driven by "war on crime" and "war on drugs" rhetoric set by political leaders, police officers have increasingly taken on the psyche of soldiers. There's a pervasive and troubling "us versus them" attitude in policing today. Policing has become more reactionary, more aggressive, and it's poisoning the relationship between the police and the communities they serve.

I should add that I don't think police officers themselves are to blame for this, nor, obviously, are all police officers guilty of it. These are problems spawned by 35 years or so of bad policies set by politicians. That's really where any reform would need to start.

DIA: Another criminal justice issue you often deal with is the use of forensic evidence. How is forensic evidence being abused in the courtroom, and what can be done to improve the way we use science in criminal proceedings?

Mr Balko: The main problem with forensic evidence is that it isn't science but it's usually presented to juries as if it were. Forensic evidence—think fingerprint matching, hair and fiber analysis, ballistics, etc—has been largely invented by and developed by police and police organisations. But when its presented in court, it's often presented with the gloss of science. It's telling that the one type of forensic evidence that actually was developed in the scientific community—DNA testing—is really the only type that's relatively certain (provided the evidence is handled properly). And it's showing us just how flawed and overstated other areas of forensics really are.

The other problem is that science is a process. It's sort of a journey toward truth. The criminal-justice system isn't shy about embracing new theories during criminal trials, but once the trial is over, the system puts a premium on finality. The courts set the bar very high when it comes to overturning convictions won in part or in whole based on science we now know is junk. Bite-mark analysis is a great example. Lots of people were sent to prison in the 1990s thanks to a small cadre of self-proclaimed bite-mark specialists. We now know there's simply no scientific support for the idea that you can match bite marks in skin to one person's teeth, especially to the exclusion of everyone else. Another good example is recovered memory psychoanalysis, which was responsible for dozens of wrongful convictions in the 1980s.

As for reform, I think we need to subject forensic evidence to the scientific method, at least to the extent that it's possible. The work of crime lab technicians and medical examiners should be tested from time to time by private labs, but without letting them know when they're being tested. Expert witnesses should be subject to statistical analysis, blind tests, and competency tests. If a medical examiner is diagnosing a disproportionately high percentage of infant deaths as homicides, for example, that would be a red flag for further investigation. Judges need to familiarise themselves with the appropriate accrediting organisations in the various forensic fields so they don't allow frauds and charlatans rubber-stamped by disreputable certification mills to testify in their courtrooms. Roger Koppl of Fairleigh-Dickinson University wrote a terrific paper for the Reason Foundation (which publishes the magazine I work for) with some other good ideas for reforming the forensics system.

DIA: Beyond the two discussed above, what are the most critical flaws in America's criminal justice system?

Mr Balko: Incentives. At every step in the process, the incentive is toward putting people in jail. And there's almost no penalty at all for state actors who overstep their authority. Police departments, for example, get federal anti-drug grants based in large part on how many people they arrest on drug charges. After the botched drug raid in Atlanta a few years ago in which a raiding police team shot and killed an innocent 92-year-old woman, we learned in subsequent investigations that officers had monthly quotas for drug arrests and drug seizures. Ed Burns, the former Baltimore cop and co-creator of the magnificent HBO show "The Wire", talks about this quite a bit.

It's also true of forensics. If a crime-lab technician reports to the local DA, there's always going to be some pressure—subtle or overt—to tell the prosecutor what he wants to hear.

But the incentive problems are most apparent with prosecutors. Prosecutors get no credit for cases they decide not to bring, either because of a lack of evidence or because pressing charges wouldn't be in the interest of justice. They're only rewarded for winning convictions. That's what gets them promoted, or re-elected, or gives them the elevated profile to run for higher office. Every incentive points toward winning convictions. And particularly with prosecutors, there's really no penalty at all for going too far to get a guilty verdict. One real disservice the Duke lacrosse case did for the criminal-justice system is it put in the public consciousness the idea that bad actors like Mike Nifong are regularly disciplined for misconduct. In truth, that case was really exceptional.

There have been a few prosecutorial misconduct cases before the Supreme Court over the last few years, and what's really striking when you read through the briefs is just how rarely prosecutors are sanctioned in any way, even for egregious misconduct. Not by courts, not by bar associations, not by state attorneys general. The Innocence Project estimates that prosecutorial misconduct factored into about a fourth of the wrongful convictions that organisation has helped expose. None of the prosecutors in those cases faced any serious sanction. It's impossible to sue a prosecutor, even if he intentionally withholds exculpatory evidence that sends an innocent person to prison. The Supreme Court will rule this spring if prosecutors who manufacture evidence that sends an innocent person to prison can be sued. I think a lot of people would be rather shocked to hear that such a notion would even be open to debate.

Most prosecutors are well-intentioned, honest public servants. But it's deeply troubling that those who aren't are almost never held accountable, and in fact are often re-elected, appointed as judges, or go on to get elected to political office.

DIA: Your blog does a great job of curating infuriating stories about injustices in today's system. What is the worst case that you've come across?

Mr Balko: I'd say it would have to be the legacy of Steven Hayne, the Mississippi medical examiner I've been reporting on for a few years now [see here]. Hayne has testified in 80-90% of the homicide cases in Mississippi for the last 20 years. He has also testified in Louisiana. The guy admits under oath that he does some 1,500-1,800 autopsies per year, several times more than the maximum recommended by professional organisations (250-300 per year). We already know of two men who served close to two decades each in prison because of his testimony who were later exonerated by DNA. His workload, testimony, and general practices are condemned by just about everyone in his profession. The guy has done incalculable damage to Mississippi's criminal-justice system. And its civil-justice system, for that matter. He also testifies in medical malpractice and wrongful death cases.

But no one in Mississippi seems concerned. Mr Hayne was effectively barred from doing autopsies last year, but he continues to testify in Mississippi's courts. He just testified last week. And state officials refuse to go back and look at old cases that may have been corrupted by his testimony. In fact, the state's Supreme Court once again vouched for his credibility as an expert last April, even after all of this had come out about him. When you think about 20 years and thousands of cases, between the innocent people he may have sent to prison, the guilty people his findings may have allowed to remain free, and the millions of dollars his testimony may have permitted to change hands in civil cases, it's hard to think of another person who could have done more damage to the criminal-justice system—particularly someone who doesn't (and never has) held any sort of public position.

DIA: A lot of politicians pay lip service to the principles of smaller government, lower taxes, and more freedom. Yet the result is often the opposite. As a libertarian, do you ever get frustrated with the lack of representation for your views in the halls of government? Is there anything that can be done to improve the standing of libertarians?

Mr Balko: In theory, libertarians share about half of our positions with the right, and about half with the left. Broadly speaking, we're social liberals and fiscal conservatives. The problem is that once in power, neither side pays much heed to the issues they have in common with libertarians, because that would require them to voluntarily put limits on their own power. And politicians don't generally seek higher office for the purpose of limiting what they can do when they get there. So the libertarian stuff is where they're most willing to compromise. And it's what they're least willing to spend political capital defending.

So we saw George W. Bush hold the line on social issues, but completely sell out on federal spending, regulation, and general growth of government. We're seeing the same thing with Barack Obama, only in reverse. I put up a blog post at Reason about this a few months ago. Obama's holding fast to his campaign promises that expand the size, scope, and power of government. The few promises he made that involve limiting government in some way—generally on social and civil liberties issues—are the promises he's been less interested in keeping. This isn't really surprising. But it speaks to the difficulty libertarians have in getting their ideas taken seriously. It's made worse by the fact that libertarians by definition generally aren't interested in seeking political power. That leaves public office and the reins of power open to those who crave it.

That said, I think there's reason for some optimism for libertarians. The generations raised on the internet will be more educated, aware, and informed than any before them, and I think that has instilled in them some naturally libertarian instincts, particularly when it comes to issues like government transparency, accountability, censorship, and police power. Perhaps I'm a bit pollyanna-ish, but it's at least possible that once the Obama administration proves just as inept, corrupt, and hopeless as the Bush administration, the younger people who flocked to Obama will start to understand that the problem isn't who's running government, it's that government power itself corrupts--and that we're better off keeping as much of our lives as possible off limits to the whims of politicians instead of this repeating cycle of putting all of our hope into the idea that someday, the right politicians will finally get elected.

Public sentiment on the drug war and the criminal-justice system in general I think is shifting. Gradually, but it's shifting. Technology also always seems to be several paces ahead of government when it comes to battling censorship and expanding choice, commerce, and opportunity. Most importantly, I think technology is adding a level of transparency to government we've never seen before, from crowd-source analysis of those 1,000-page bills Congress is so fond of sneaking through, to Google's recent move to make case law available and searchable to the public, to the proliferation of cell-phone cameras and the resulting documentation of police and government abuses for the world to see--be it the Iranian government's crackdown on democracy protesters or a Bay Area cop's killing of a BART passenger.

George Orwell wrote of government power, "If you want a vision of the future, imagine a boot stamping on a human face—forever." He may still be right, but there's now a decent chance someone will be there with a cell-phone camera to post it on YouTube. And exposing abuse of power is half the battle.