Among the 50 most populous countries, the United States and Nigeria are the only nations in the world with exactly two political parties represented in the national legislative body. (For a list of the 50 most populous countries and the number of parties represented in their legislative bodies, click here.) Election laws and debate practices in the United States make it extremely difficult, almost impossible, for the voters to launch a new major party. Consequently, in election after election, there is no realistic chance for a new party to displace either the Republican or Democratic Parties. This state of affairs is partly because the U.S. Supreme Court, for the last 23 years, has fostered the status quo and upheld laws that protect the two major parties from competition. Starting in June 1992, the U.S. Supreme Court has refused to hear every case filed by minor party or independent candidates against restrictive laws that bar them from the ballot or debates or otherwise injure them, with only a single exception: a case from Georgia in which Libertarian Party candidates challenged the state law requiring all candidates for state office to be tested for illegal drugs. Setting aside that exception, there are now 54 examples when minor parties and independent candidates asked for help from the court, and were refused, during the period from 1992 to the present. (To see a list of such instances that occurred before 2012, click here.)
But during the same period, when minor parties or independent candidates won in the lower court, and the state that lost the case then asked the Supreme Court to hear an appeal, almost half the time the U.S. Supreme Court took the case and reversed the decision, to the detriment of voters who support alternatives to the two major parties.
To be fair, since 1992, I must mention there are two instances when the Supreme Court heard cases that minor parties had brought after losing in the court below, but in both those instances, the two major parties were also in the case on the same side as the minor parties. But when minor parties or independent candidates are alone in bringing the case, and don’t have the Democratic or Republican Parties as co-plaintiffs, since June 1992, they have always lost in the U.S. Supreme Court.