Two of Labor's prime primary contenders disqualify each other ultra-convincingly. Ehud Barak, with unassailable justification, homes in on Amir Peretz's devastating lack of military expertise. Equally justly, Peretz blames Barak's "brilliant" unilateral midnight flight from Lebanon in 2000 for emboldening Hizbullah, allowing it to improve positions, amass a monstrous rocket arsenal and place Israel's northern third within range of terrorist barrages. Both are indisputably right and culpable for what went wrong in the Second Lebanon War. Barak was the failure's progenitor, whereas Peretz made a bad situation incalculably worse. That either of them again dares vie for the national leadership is galling. Any Laborite who casts his ballot for one of these outrageous incompetents should have his head examined. This leaves us with ostensible new broom Ami Ayalon - promising, charismatic, self-assured and one who toots his own horn while maintaining the disingenuous old-time Labor facade of unpretentiousness. Ayalon - who negotiated (with his no-account Palestinian "partner" Sari Nusseibeh) an "understanding" every bit as delusional as Yossi Beilin's Geneva Accord - markets himself simultaneously as a peacenik and a formidable security guru. He's the ex-general who can make up for Peretz's preposterous deficiencies, yet isn't tainted like the supercilious Barak with strategic fiascos. Considering how utterly unworthy his competition is, Ayalon appears like Labor's last great hope. But he isn't. He's a disaster waiting to happen. As Barak and his successor Amram Mitzna amply proved, military rank is no guarantee of common sense. If anything, Ayalon makes both Barak and Mitzna look exceedingly smart. They at least haven't produced anything like the chatterbox gaffe he managed at a recent party campaign rally. That was the venue Ayalon chose to divulge that Israel possesses submarines capable of effectively averting the Iranian nuclear threat. Ayalon, for anyone who may forget, was Navy OC. In all likelihood he knows whereof he speaks. His blabs about marine warfare carry credence. But the illustrious admiral apparently failed to recall that loose lips sink ships, including vessels that move stealthily below the water's surface. As even buck privates should comprehend - never mind the top brass - some things are better left unsaid. Even when one is trying to impress and win votes, prudence should override the temptation to prattle. BUT AYALON also revealed something else, which indelibly stains his ethical reputation and should exclude him forever from high office. If the submarine disclosure is irresponsible, then what he said about Margalit Har-Shefi indicates extreme callousness. In any normal democracy he'd be pilloried, but in this country, whose media are irredeemably biased, any uproar is invariably selective. The press without exception always protects the Left's darlings, and Ayalon unquestionably falls into that category. Hence no fuss was generated by the wanna-be Labor leader's admission that he stood by and allowed the conviction of a young girl he knew to be entirely innocent. Har-Shefi, just 19 at the time, was arrested after Yitzhak Rabin's assassination in 1995 because she was Yigal Amir's classmate and friend. The prosecution alleged she knew of Amir's intentions yet failed to make that fateful call to the police. Interrogators would have none of her cheeky insistence that she cannot read minds. They hounded Har-Shefi and vilified her, while lackey journalists avidly colluded by amplifying the calumny. The hapless teen was raked over the coals even for such transgressions as changing her haircut or attending a bat mitzva. She was fired from her job and became a despised public enemy. If Amir was Clyde, Margalit was demonized as his Bonnie. Her ordeal dragged on for years. She was tried, convicted, lost successive appeals and was imprisoned only in 2001. Throughout, she vehemently denied having any advance hint of Amir's scheme. The majority of judges, presumably having accessed her innermost consciousness, ruled otherwise. It was her word against their opinion. Not a shred of actual corroborating evidence existed. During her association with Amir, his record was unblemished. His other friends, exposed to the same rhetoric from him, weren't prosecuted (to say nothing of the fact that Shin Bet agent-provocateur Avishai Raviv is yet to pay for his pivotal role in the conspiracy). Margalit was the only settler in Amir's entourage, making her the perfect scapegoat. Margalit's parents received hate mail, like a letter accusing them of having raised a "malignant tumor in your criminal settlement." Upon her release, she was greeted by protesters who screamed "murderer" at her. During that entire prolonged torment, Ayalon could have ended the willful abuse in an instant. He verified this himself when boasting to an Ashkelon audience that he possessed "intelligence information" clearly establishing that "Har-Shefi didn't imagine what Amir planned. I know - I was Shin Bet head." Ayalon indeed took over the Shin Bet from Carmi Gillon shortly after the assassination and stayed on for five years, precisely when poor Margalit sought desperately to extricate herself from the crime of befriending the wrong coed. Both Ayalon and Gillon belatedly opined that Har-Shefi wasn't guilty and supported presidential clemency to reduce her sentence by a third (after the parole board refused). However, in real time Ayalon allowed his agents to lie prodigiously and incriminate a faultless adolescent without lifting a finger. All he had to do was dial state attorney Edna Arbel (since promoted to the Supreme Court) and let the poor kid off the hook. The case couldn't be pursued were the serving Shin Bet chief upright and insistently so - whether publicly or behind closed doors. His unthinkable omission makes Ayalon liable for obstruction of justice and complicity in a frame-up. It must be liberating to lack a moral compass.