No two ways about it: Donald Trump has scored a tremendous victory. He is right to rejoice. He is correct in asserting that he has been vindicated. Legal experts might quibble over the exact scope of the Supreme Court decision, but the bottom line is that the most august institution in the land has endorsed Trump’s authority to ban immigration on the basis of religion, especially if it happens to be Islam. It’s a big step forward for Trump, a giant step backward for liberal America.

>> U.S. Supreme Court upholds Trump's travel ban

The 5-4 decision by the Court’s conservative majority underscores how far the United States has evolved since Trump’s December 2015 election campaign call for a “shutdown of Muslims entering the United States until our country’s representatives can figure out what the hell is going on.” Back then, the reaction was overwhelming revulsion, which encompassed most Republican presidential candidates as well as world leaders, including, hard to believe now, Prime Minister Netanyahu. Two and a half years later, Trump’s racially-tinged edicts have been whitewashed by the Supreme Court as Republicans are lauding its decision as a confirmation of presidential authority. In the eyes of the so-called enlightened world, America is receding into darkness.

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Chief Justice John Roberts and his conservative colleagues Samuel Alito, Clarence Thomas, Anthony Kennedy and Neil Gorsuch preferred to ignore the religiously prejudiced origins of the Trump ban and to focus on the modified executive orders and presidential proclamations that sought to render it palatable to the judicial system. They buried their heads in the letter of Trump’s edicts, rather than dwell on their spirit and intent. But no matter how many fine points are made to differentiate between Trump’s original blanket ban and the restrictions now placed on immigration from eight countries, six of which are Muslim, the odious bottom line remains the same: A thinly disguised populist appeal to the baser instincts of Muslim-fearing Americans has now become the law of the land.

The decision sends a wake-up call to liberal America: Your institutions won’t save you. They are all ideologically corruptible. A Supreme Court that is made up of political appointees, that was “saved” from a liberal majority by an unscrupulous Majority Leader Mitch McConnell, who shamelessly blocked the appointment of Obama appointee Merrick Garland for over a year, cannot be relied on to uphold liberal values or interpret the Constitution in their light. It is a safeguard built on shifting sands, as it has been throughout American history, from sanctioning slavery and racial segregation to ensuring freedom of speech and a woman’s right over her body.

>> Dumber and more counterproductive: Israel's travel ban is worse than Trump's | Opinion

As the Israeli experience over the past decade has shown, a system of checks and balances can only survive if all of its players cherish it and play by its rules. Just as Benjamin Netanyahu’s right-wing coalition has served as his rubber stamp, enacting successive laws that enshrine the occupation and undermine Israeli democracy, so has the GOP majority in Congress increasingly bowed its head before Trump’s whims and impulses. In both cases, the leaders’ hypnotic hold over their political base is the tool with which they can browbeat even the most moral of politicians into submission, with the exception of the few who are willing to give up their careers for their conscience. Over the years, principled troublemakers are eased out, replaced by opportunists and kowtowers who learn by example how to twist their principles in order to get ahead.

In this regard, Special Counsel Robert Mueller may turn out to be the Last of the Mohicans, the last man standing before Trump has his way with American law and order. Tuesday’s SCOTUS decision, however, is a shot across the bow for Mueller as well. When it is called upon to adjudicate the scope of Trump’s authority to resist the special counsel, as it most certainly will if the president feels threatened by Mueller’s findings, the court could once again ignore the authoritarian writing on the wall and opt in Trump’s favor.

And while America’s civil society has shown outstanding resistance and resilience throughout Trump’s first 520 days in office, it too is susceptible to disillusionment and fatigue. The more Trump gets his way, the less his opponents will be able to summon the energy to mount effective campaigns to block him. In the end, even the most dedicated and idealistic public activists will slowly wither away, opting to cease and desist rather than engage in what may increasingly seem like exercises in futility.

In the end, only American voters can stop Trump in his tracks. Only the voters can prevent the United States from slowly but surely evolving into Trumpistan. The crunch time will come in the Congressional elections in November, which could yield a Democratic takeover of the House of Representatives. Voters, however, are notoriously unreliable, as any peace-loving, democracy-cherishing Israeli leftist can tell you.

Democrats would be wrong to underestimate the enduring appeal of ethnocentric nationalism and the persistent power of incitement against foreigners and minorities. Both have made Netanyahu into Israel’s longest serving prime minister and kept the right wing in power for most of the past 40 years. If Trump isn’t stopped soon, Trumpism could rule for decades, aided and abetted by the highest court in the country.