Border policeman Rami Zoari, 20, was murdered Thursday night and the policewoman on duty with him was seriously wounded in a shooting at a roadblock that was being manned late at night, contrary to their commander's best judgment. What befell the two young conscripts was, top Border Police officials said, "a disaster waiting to happen." The victims were described as "sitting ducks." The only reason they were there at night, according to the Israel Police's Insp.-Gen. David Cohen and Jerusalem District head Cmdr. Aharon Franco, was a High Court ruling that the police had no option but to obey. The roadblock in question is the smaller and more vulnerable of two checkpoints into Shuafat in northern Jerusalem and is earmarked for pedestrians only. It handles less traffic than its larger neighbor 200 meters away, whose guards are protected by concrete barriers and narrow approach tracks, which make passage possible only in single-file. Without such roadblocks, assailants - such as those who perpetrated the latest attacks - would be free to enter Jerusalem and beyond. The police had wanted to channel all movement after sundown to the larger crossing. But the Supreme Court, sitting as the High Court of Justice, ordered the smaller access route between Shuafat and Givat Ze'ev open 24 hours a day, out of concern for the quality of life of Shuafat's residents. "If it were up to me," Franco declared, "this crossing would have remained closed, but the Supreme Court imposed its will." The police and the IDF are security professionals, whose judgment and experience ought to serve as guidelines for judicial authorities. Those authorities, in turn, presumed to be as concerned about the safety of all Israelis as any branch of government, ought not to function like detached and indifferent UN observers. That does not mean the courts need routinely accept all such defense establishment recommendations. But it does mean that the greatest caution should be exercised when they are disregarded, as the court seeks to balance security needs with the imperative for "proportionality." The recurring judicial argument is that minimizing the grave risks cited by the defense authorities may cause "disproportionate interruption" to the Arab population's "fabric of life." However, there are no precise and objective gauges for measuring such proportionality, and all too often humanely-motivated court verdicts have devastating results. In 2004, for example, the court prevented the IDF from leveling a building overlooking the Kisufim junction leading to Gush Katif. That building was a snipers' nest and launching-ground for repeated attacks on Israeli vehicles. On May 2, 2004, Fatah terrorists exited it to stop a car driven by pregnant mother Tali Hatuel and her four young daughters. All were executed, one by one, at point-blank range; even the homicide of the eight-month fetus was "verified" by the killers. This is not to suggest that the court is directly liable in the Hatuels' slaying, in last week's Shuafat shooting, or for similar atrocities that took place in between. Those who bear the direct guilt, of course, are the terrorists and those who dispatch, incite and tolerate them. But the Supreme Court's decisions were contributing factors in calamities that the defense establishment had foreseen. This is not an exercise in Monday-morning quarterbacking, but a question of principle: To what degree should the judicial branch, which has no direct security expertise, override the security judgments of the executive branch? By the same token, it must be asked whether the justices are right to regard themselves as capable of ruling on where exactly to position every stretch of the security barrier regardless of the topography, and whether they are receiving the necessary expert input on these life-and-death decisions. Plainly, nonsecurity considerations, such as the impact on Palestinians' mobility, need to be taken into account. Plainly, too, however, the IDF makes clear that it does seek to balance security needs with the need to avoid unnecessary hardship to innocent Palestinians. No one has a monopoly over the best judgment in such life-and-death decisions. But the genius of democracy is seen not only when it grants the judiciary the power to override the executive branch. It is also seen when the judiciary sees fit to restrain itself, and chooses to act not as an executor, but as the arbiter of questions of law. The Shuafat attack and others are an indication that while there is a danger that the IDF might err on the side of Palestinian inconvenience, the Supreme Court might err on the side of risking Israeli lives.