Exhibit 1A in Prime Minister Netanyahu’s case to reform Israel’s judiciary could hardly be more clear, or come at a better time. On Wednesday morning the Jewish state’s Supreme Court ruled 10-1 that the leader of the Shas Party — Aryeh Deri — could not serve in Mr. Netanyahu’s new government. Citing his conviction for tax fraud and subsequent suspended prison sentence, the court ruled that his appointment would be “extremely unreasonable.”

The only thing unreasonable about Mr. Deri’s appointment is the overreach of the court. As we’ve noted, one of Mr. Netanyahu’s proposed changes is to neutralize this ability for the court to veto appointments on “reasonability” grounds. Weeks ago, Deri was sworn in as interior minister, vice prime minister, and health minister. The Knesset recently amended a law to allow Mr. Deri to serve because his sentence was suspended, not served. 

Israelis were transfixed Wednesday night by images of Mr. Netanyahu arriving at Deri’s home at Har Nof, a suburb of Jerusalem, for a parley with an armada of security. One can only guess as to their conversation. Israel’s justice minister, Yariv Levin, has said that the court’s decision “annulled” the will of the voters and that he will “do everything necessary to fully repair the terrible injustice done to Rabbi Aryeh Deri, Shas and Israeli democracy.” 

We carry no brief for Deri. He was convicted of bribery and fraud in 1999 and served two years behind bars. The latest contretemps centers on tax offenses. Before his run-ins with the law, he was a wunderkind, forging a bond with Jewish voters of Middle Eastern origin that made him Israel’s youngest minister at age 29, and making Shas a kingmaker. Since the death of Shas’s founder, Rabbi Ovadia Yosef, Deri has repeatedly won elections for the Knesset. 

Israel’s constitutional crisis, now fully joined, has nothing to do with Deri’s peccadilloes, and everything to do with power. The Supreme Court’s president stated that his appointment was “stained by a flaw of extreme unreasonability and it is in serious contradiction to the basic principles that should guide the prime minister when he appoints ministers.” In other words, judges decide who serves in the  government that could reform the court. 

The court cited an avowal  Deri made as part of his plea bargain that he would refrain from handling public funds. Those of us weaned on separation of powers and limited government — the American way — cannot help but look askance at this wielding of veto power over the voters, who cast their ballots on, at least in part, judicial reform of a court bound by neither a Constitution nor the requirement of standing. 

One of the great legal sages, Eugene Kontorovich, labels the decision “insane” and sees the Supreme Court acting to “decapitate” the government before it can work to cut the judges down to size. If Deri in fact violated his plea deal, that case would be one for a prosecutor to make to a trial judge. Surely, Mr. Kontorovich adds, Deri is not the first nor the last politician to lay claim to a role he promised to abjure.  

Rough analogues present themselves from the American scene. In Powell v. McCormack, our Supreme Court ruled that efforts to block a representative from being seated ran afoul of the Constitution, but only after meditating on whether it could weigh the matter. Our 14th Amendment allows for disqualification, but only under precise conditions and predicates, not under a “reasonableness” catch-all. 

A showdown appears imminent. If Mr. Netanyahu bends to the court, his coalition will quake. The Times of Israel reports one minister quipping that “if Aryeh Deri is not in the government, there is no government.” The prime minister, himself facing corruption charges that limit his ability to serve in any post besides premier, hopes that in flexing its muscle, the court has justified the movement to reassert parliamentary principles. 

This is of American concern for reasons that go beyond an affinity for Israel. This battle over the role of courts in parliamentary democracies is raging all over Europe. Those who are concerned with the vibrancy of liberal democracy will recognize that it is the boundaries of power that bestow legitimacy on its exercise. Israelis knew Deri and Mr. Netanyahu when they voted for them. Unreasonable choices they may be, but ones made democratically.