Since late 2008 the cricket world has hotly debated the Decision Review System, or DRS. Technology had long been used by the commercial television broadcasters - especially Australia's Nine Network - to enhance their viewers' experience of watching the game. Well before DRS, fans had become accustomed to having umpiring decisions scrutinised by Snicko, Hawk-Eye and Hot Spot, all applied in extreme slow-motion.

It was inevitable that this technology would be employed to actually review umpires' decisions. Fans and commentators had always been harsh on umpires when available evidence suggested they had made poor decisions. But umpires were sitting ducks against the tides of criticism that came from living rooms - and journalists' pens - as each of their mistakes was isolated, magnified and replayed over and over when subject to advanced audio-televisual technology. Since 2006 tennis line-calls had been subject to a version of Hawk-Eye which was more or less successful in reviewing close decisions without detracting too much from the flow of the game. And cricket's initial foray into the technological review of umpiring decisions - the "third umpire" review of run-outs and stumpings - had been working well since 1992, in much the same way that controversial tries in rugby had been subject to replay and review since 1996.

But DRS soon proved far more problematic than the first generation of TV-based review. The BCCI continues to oppose it, and the ICC, while endorsing the system, leaves the final decision up to the teams involved in each match. Both teams must agree to use DRS, otherwise it isn't used. India has copped a lot of flak for its recalcitrance. When its team toured Australia during the 2011-2012 summer, the host nation's fans made little effort to hide their frustrations at the visitors' refusal to accept the inevitable.

After a bewildering series of DRS decisions in the current Ashes Tests, Australian fans no doubt have more sympathy with India's position now. Usman Khawaja's dismissal in the first innings of the Third Test had the feel of 'enough is enough'. DRS may be the least of Australia's problems in England, but it does provide an external focus for its fans' frustrations. Their most urgent debates are immediately suspended when DRS throws up yet another howler. Twitterverse explodes with indignation at the injustice of it all. Even the Prime Minister, Kevin Rudd, felt the need to tweet about the Khawaja clanger.

DRS was sold to players and spectators on the sole basis that it would practically eliminate the shockingly bad umpiring calls. It patently does not do that, for two reasons. The first relates to the system within which its use is embedded. The ICC decided to leave the use of DRS reviews up to the players. So as to prevent every single decision being reviewed, teams were necessarily limited to two unsuccessful reviews per innings - just as tennis players are limited to three challenges per set. What this means, of course, is that once a team has spent its reviews, umpiring howlers against it go uncorrected. This system could have worked spectacularly well, because it incorporates an additional level of tactical play. But it turns out that the vast majority of the cricket world appears to value accuracy over tactical play, at least on this issue.

The second reason why DRS doesn't eliminate shockingly bad umpiring calls is to be found at the intersection between the technology and its use by humans. It is rarely accepted that the technology is not and cannot be 100% accurate. Hot Spot relies on a heat signal produced by the ball touching the wood of the bat or the padding of the gloves. Produced originally for military application, it is fallible on a number of grounds, including the fact that the cameras still operate on a frames-per-second basis and so leave open the possibility that the conclusive frame is nonexistent. Hawk-Eye works on principles of geometric triangulation: the vision from six high-performance cameras is triangulated to estimate the future path of the ball based on its existing path before it hits an obstruction. Used for leg-before-wicket reviews, it is far more problematic than Hot Spot, because most of the time the input information - the actual path of the ball before it thuds into the batsman's pad - is less than a metre, given that the ball has just bounced on the pitch. The margin for error for Hawk-Eye in tennis (where the "input" data can be taken all the way from its impact with the racquet of the player at the other end of the court) is 3.6 millimetres, which is extraordinarily accurate until you consider that decisions are often confirmed or overturned on margins well within that margin for error. But in cricket, where there is much less input data, the margin for error is much larger.

Because we live in an age dominated by the ideology of technological progress, and because we tend to believe what we see (especially if it is presented to us with deceptively uncomplicated clarity - think of the crisp, animated images of the Hawk-Eye flight path in tennis and cricket reviews), we prefer to expect a level of accuracy from the technology that's just not possible. The ICC implicitly acknowledges the relatively large margin of error in its application by having the third umpire defer to the field umpire's original call when Hawk-Eye indicates that less than half the ball would have hit the stumps, or pitched in line with them. But fans (and players) just see almost half the ball hitting the stumps and wonder why the third umpire can't overrule the field umpire on that basis.

"Implicit in the claim that DRS would improve umpiring decisions is the expectation that DRS will add value, that it will not detract from the experience of playing and watching cricket."

Added to these expectations are the practical difficulties in operating the review technology as a third umpire. Much of the time, the umpire is still making judgements on the strength of two-dimensional representations of three-dimensional realities, while being seductively deceived by the strength of the images in front of him. And on what basis is he to make his decision? Should the benefit of the doubt continue to go to the batsman, as it does when the field umpire makes a decision? What is the standard of proof that he requires: the balance of probabilities, or being beyond reasonable doubt? Should his starting-point be the decision as made by the field umpire, or should he start from scratch with the evidence before him? From time to time the ICC seeks to clarify these questions. Fans and players are mostly in the dark.

Part of the reason the Khawaja decision by third umpire Kumar Dharmasena was received so badly is that while the technology appeared to show that the ball passed Khawaja's bat without hitting it, Dharmasena seemed to be looking for conclusive, positive evidence to overturn field umpire Marais Erasmus's original decision, which was "out". And almost by definition, the technology cannot produce positive evidence to show that ball did not hit bat. It's the philosophical equivalent of trying to prove that it did not rain on Tuesday, or that Santa Claus doesn't exist: negative proofs are extraordinarily difficult. Which rule was Dharmasena applying as he reviewed the replays? Australia has requested a "please explain" from the ICC, if only to clarify the process used by third umpires in DRS reviews.

The only claim that can be legitimately made about DRS is that it improves the quality of umpiring decisions on average. It is impossible to know to what extent it achieves this, because we have no window into the objective reality of what happens on the field. But advocates of DRS point to this unarguable claim, and for them, that is enough to justify its continued application. DRS advocates also tend to place their faith in the inevitability of technological progress and make the additional claim that the objective accuracy of DRS can only improve in the future.

But these claims ignore a nagging doubt in the minds of DRS sceptics and opponents. Implicit in the claim that DRS would improve umpiring decisions is the expectation that DRS will add value, that it will not detract from the experience of playing and watching cricket. In 2009 this implicit claim was unarguable: better umpiring decisions would mean better cricket. But this Ashes series has seen doubts about this implicit claim crystallise for two reasons. Firstly, it seems that DRS has sharply raised players' and fans' expectations of good umpiring: even if it could be shown that the average quality of umpiring decisions has improved, this average has not risen commensurate with our expectations. And secondly, the long delays associated with each review, together with the frustrations inherent in the two-review limit, have led to an overall increase rather than decrease in the frustrations inherent in watching and playing cricket.

While nothing is done, the calls for some kind of official response will become deafening. And yet it is now extraordinarily difficult to know what to do from here. At one end of the debate is the call to scrap DRS entirely. If this happens, the situation would revert to the way it was before 2009: extended, slow-motion, close-up replays would show particular umpiring decisions to be shockers, and nothing could be done about them. I for one would be comfortable with that, but I expect that umpires and players whose livelihoods depend in part on the quality of umpiring decisions would not. The only solution to that problem - banning telecasters from using technology to critique field umpires' decisions - is untenable on commercial, practical and commonsense grounds, and perhaps it even violates the way we like to understand our freedoms of innovation, enterprise and even communication. At the other end of the debate is the suggestion that teams be allowed unlimited reviews, or that the power to review a decision be placed with the field umpires themselves. Both would have the same ultimate effect: every single decision would be reviewed. This would quickly prove untenable. Australia trialled this in its domestic one-day competition last summer, and abandoned it part-way through: it made field umpires redundant, and it slowed the momentum of play to such an extent that even fans of a game its detractors compare to watching grass grow were driven to distraction.

I began writing this article expecting to conclude it with a call to abandon DRS. But, as the technological ideologues say, the genie is well and truly out of the bottle. Like representative democracy, DRS may well present the "least worst" of all possible alternatives, given current constraints. Some tinkering may improve it, or not: what seems vital is that the ICC and/or its Elite Panel of Umpires ensures that the cricketing world - including umpires, players and fans - better understand the limitations of the technology and the rules which govern its application. Australian commentator Jim Maxwell has suggested that the third umpire has an inherent conflict of interest in wanting, above all, to confirm the decision of his on-field colleague, and that this conflict requires third umpires to be drawn from a pool different to that of field umpires.

Perhaps. Whatever happens to DRS from here, it will stay, and largely in the same form. The cricket world will need to come to terms with the fact that science has introduced to it a tool which at the same time adds to and detracts markedly from the enjoyment of watching and playing the game. Cricket has survived other such innovations: bodyline; professionalisation; commercialisation; Twenty20. I daresay it will survive DRS too.

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