Last week, we examined reasons why the very nature of drug testing technology — which cannot eliminate false positives and false negatives at the same time — means it will never be a perfect mechanism for catching cheaters. This may come as no big to surprise to anyone who remembers the famous Nike commercial featuring video of Lance Armstrong taking a drug test. “What am I on?” Armstrong asks rhetorically. “I’m on my bike, busting my ass six hours a day.” He was also on a raft of drugs, yet passed hundreds of tests. Certainly, testing technologically has progressed since then and will continue to do so. But even if technological holes are closed, logistical loopholes may remain. Here are four holes large enough for Lance to ride a bike through:

1. The Dog Was Eating My Homework...While My Doorbell Was Broken

When athletes take small doses of synthetic hormones, the window during which they might fail a test is very short — often just hours. So it’s critical that athletes don’t know when the tests will occur. To facilitate year-round, unannounced testing of a limited number of top athletes, the World Anti-Doping Agency calls for “whereabouts requirements.” Beginning in 2009, potential Olympians had to fill out forms letting anti-doping authorities know where they would be for at least one hour each day — between 6 a.m. and 11 p.m. — for the next few months. (An athlete’s whereabouts calendar can be altered, and the U.S. Anti-Doping Agency even has a mobile whereabouts app.) Still, athletes can miss three tests in 12 months before they face a sanction. It’s only fair to give some wiggle room — any idea where you’ll be three Tuesdays from now? — but it means athletes can sometimes avoid the testers by claiming to have stepped out briefly or that they didn’t hear the doorbell. Or, as retired professional cyclist Tyler Hamilton — and admitted former doper — once succinctly summarized a low-tech method of chicanery: “We hid.”

2. Testing Infrastructure? What Testing Infrastructure?

The World Anti-Doping Agency itself is not — as is commonly misunderstood — set up to drug test athletes around the world. WADA was launched just before the turn of the millennium to coordinate anti-doping efforts and rules around the world. The agency conducts research to better detect ever-more advanced doping, accredits labs that want to become certified for drug testing (and strips accreditations if labs don’t maintain certain standards), and keeps the World Anti-Doping Code. The Code, includes the list of banned substances and the methods and rules for how anti-doping efforts should be conducted by sports federations and countries. It was implemented before the 2004 Olympics and has been updated several times. So WADA simply keeps the Code; it’s up to the Olympic committees, national and international sports federations, and anti-doping bodies in each individual country to actually implement it. Typically glacial bureaucratic movement has ensued. In one prominent instance, Renee Anne Shirley, former executive director of the Jamaica Anti-Doping Commission, pointed out that limited staff and expired testing kits led to a total halt to JADCO’s out-of-competition testing in the three months before the 2012 London Olympics. (Athletes were still subject to testing by international governing bodies.) Implementing agreed upon anti-doping practices is still a fairly new and definitely evolving venture for plenty of countries and sports organizations, and it’s still a global patchwork.

3. TUE

It’s an abbreviation for “Tuesday” to you, but any athlete who sees those letters immediately thinks “therapeutic use exemption.” Athletes have to be allowed to care for their health, and the TUE system allows them to apply for permission to use substances or medical procedures that would normally be restricted, ranging from corticosteroids and stimulants to IVs. The trouble is that any process by which athletes can gain permission to use potentially performance enhancing drugs also provides a possible anti-doping loophole. Perhaps the most stunning recent TUE revelation was that Yankees slugger Alex Rodriguez was actually given permission at one point to use synthetic testosterone, and then to use the drug clomiphene citrate, meant to boost testosterone in men who are not producing enough naturally. The Ultimate Fighting Championship also gave out a rash of exemptions for testosterone, with most athletes claiming they needed it because they had low testosterone for their age. In Olympic sports, an exemption for testosterone would be extraordinarily hard to come by. Simply low testosterone levels do not suffice; a rare condition — like being born without testicles or having them removed — would have to be present. But the prevalence of certain medications among athletes — like corticosteroids, both injected for pain and inhaled for asthma — has led some of the pros themselves to call for removal of the TUE process altogether, so that there would be no exemptions for otherwise restricted medication. As American distance runner Ben True recently put it: “I have a hard time with the idea that if you’re that sick and need certain drugs that you’re able to be at the top of the sport and race at the highest level. Maybe you just need to go home and rest and recover for a while.”

4. Henhouse, Meet Fox

Officials at IAAF — track and field’s international governing body — were understandably a tad defensive after a recent report by London’s Sunday Times and German broadcaster ARD that a review of 12,000 leaked biological passport tests for track athletes from 2001 to 2012 found that around 15 percent of them were doping. The governing body has a lot to lose from the perception that cheating is rife and that many athletes get away with it. It falls in line with a host of recent scandals in pro sports in which the agency charged with rooting out cheaters was unsurprisingly “surprised.” You didn’t expect Sepp Blatter to lead the charge against corruption in World Cup soccer, did you? Or the UCI — cycling’s governing body — to take down Lance Armstrong? Of course you didn’t, just like you didn’t expect Major League Baseball to interrupt the steroid-fueled home run chase — which propelled baseball back to relevance after a devastating strike — in order to bring you an important message about performance enhancing drugs.

Olympic sports are far better off than the MLB’s of the world in this regard, as national anti-doping organizations — in America, the U.S. Anti-Doping Agency, the folks who did bust Lance — do a lot of the heavy lifting. For example, they conduct out-of-competition testing, adjudicate violations, and even test foreign athletes who train in their countries. But sports federations themselves have a role as well, conducting in-competition testing (and some out-of-competition testing), educating athletes, and sanctioning rule violators. The irony, of course, is that the harder a sport attempts to police doping, the more commercial harm it suffers. A recent study found that the announcement of a performance enhancing drug violation in baseball temporarily reduces fan attendance. The NFL doesn’t disclose the substance that a player tested positive for, so many football players who fail a test claim publicly that they forgot to get an exemption for their ADHD medication. So the NFL can never seem like it has an actual performance enhancing drug problem. It’s a little like how the NHL stopped disclosing specific injuries (beyond “lower body injury” and “upper body injury”) when concussions became a cause célèbre. That way fans aren’t alerted to the frequency of concussions and the scope of the problem. It’s the kind of behavior your local economist would predict: Sports officials who stand to lose money from drug and other scandals won’t work to expose the internal problems of their sport. And as long as there are conflicts of interest in anti-doping, there are likely to be scandals akin to the reported cover-up of Russian runners’ positive drug tests. Just last week, Lord Sebastian Coe was elected as the new president of the IAAF, and mentioned that conflicts of interest, both real and perceived, must be addressed. He then promptly drew criticism for making light of concerns over his own relationship with Nike — the biggest corporate name in the sport — for which he is a paid international ambassador. (Turns out Coe is also paid by a company that makes synthetic track surfaces, raising more questions over how serious he is about conflicts of interest.)

The good news is that the organizational and human problems are largely fixable, even while drug testing remains imperfect. The missed-tests provision could be tightened to allow fewer or even no misses, even if this meant that some athletes whose dogs actually were eating their homework when the drug testers showed up would surely be sanctioned. Perhaps a system mandating short suspensions for a single missed test would deter those who are intentionally avoiding anti-doping personnel while not excessively punishing those who have a legitimate excuse. Maybe there could even be a TUE-like system of applying for exemptions when a test is missed. Speaking of TUEs, that system could be tightened as well with more stringent evaluation of athletes’ prescriptions. (And some athletes and national anti-doping organizations are calling for medications that don’t require exemptions but that are widely used to gain a performance benefit — like thyroid hormone — to be restricted.) The tricky part in all of this is that it creates more logistical work and amplifies the off-the-field burden on athletes. And while athletes in Olympic sports must detail their whereabouts, requiring those in major pro sports — with powerful players’ unions — to do the same is about as likely as the Jets winning the Super Bowl this year. So, as with testing technology in Olympic sports, the system is very far from perfect, but it’s also the best one out there at the moment.

Michael J. Joyner is a physiologist and expert in human performance at the Mayo Clinic in Rochester, Minnesota. The views expressed here are his own. Follow him on Twitter at @DrMJoyner.