Why Is The U.S. Federal Court Status Quo The Way It Is?
The short answer is that this is path dependent. The status quo was put in place in 1789 before anyone had extensive experience with large non-monarchical governments, and lifetime appointments seemed like a good idea at the time.
It is much harder to amend the constitution of the United States than it is to do so in almost any other country. It takes a large, geographically homogeneous bipartisan majority to do so (two-thirds majorities in both houses of Congress, and ratification by three-quarters of the states in the predominantly used method). When there were just 13 states, Senators weren't directly elected, and the nation's politicians had a great deal of common ground in the wake of the shared experience of the Revolutionary War against Britain and a broad consensus of shared support for George Washington as the first President, it was not obvious that it would be so hard to amend the constitution in the future, or that the federal government would evolve so much that a desire to do so would be as pressing as it is today.
But the U.S. has also, for its entire history, had partisan divides that have a strong geographic component, so that a requirement that a constitutional amendment be supported by a two-thirds majority in the U.S. Senate, or a three-quarters majority of state legislatures, provides either major political party in our de facto two party system a veto over any proposed constitutional amendment.
Nobody drafting the U.S. Constitution in 1791 (when the Bill of Rights was adopted) would have bet a nickel that it would still be the governing document with only minor amendments, 230 years later in 2021, in a country with 50 states spanning past the Pacific Coast of North America, with 100+ times as many people as it had then, a much broader franchise, and a much more powerful central government. In 1789, when the terms of federal judges were established, there was no Bill of Rights for judges to adjudicate. In 1791, the Bill of Rights was a restriction on a tiny federal government, not something that applied to all governments. Modern legal theory ascribes the application of the Bill of Rights to state and local governments to the adoption of the 14th Amendment in 1868, but the federal bill of rights wasn't applied to state and local governments with any regularity for another 50 years, and the lack of routine constitutionally based individual rights litigation made the federal courts for the first 120 years or so of the U.S. Constitution, made the federal courts significantly less important.
No Republic this large without a monarchy of this scale had lasted that long in the past without being overthrown by revolutions or invasions or becoming autocratic, and no one really expected that it would last that long this time.
This wasn't an unreasonable expectation. The previous Articles of Confederation, that was the first constitution of the United States, lasted only about a decade. The survival of the U.S. Constitution and nation in the wake of the Civil War, commenced 70 years after the Bill of Rights was adopted, was a close thing. The French Revolution started the year that the U.S. adopted its constitution and underwent numerous swings between monarchies and new constitutions for Republics in the same time frame. Most other new democracies in world history had coups or at least major constitutional overhauls in their early years of democratic self-government, even in Latin America and Liberia, where the original national constitutions of these countries were closely modeled on the U.S. Constitution.
But, because U.S. Courts have been quite influenced by political views for at least the last century and a half, if not longer, it has usually been in the interest of one party or the other to resist such a change.
No one has managed to secure a consensus to change the status quo prospectively, and not for want of trying, after the importance of the federal courts grew clear in Reconstruction (applying federal statutes attempting to end slavery and related discriminatory laws) and starting again in the early 20th century.
Pre-Civil War, the U.S. government was almost entirely funded with customs duties, and both federal legislators and federal judges routinely left their posts mid-term for more powerful positions in state and local government, and in business. There were no meaningful federal immigration laws, there was no federal welfare state, there were few federal protections for individual rights, and there were few federal criminal prosecutions.
Notably, in state courts in the U.S., lifetime appointments are rare. It is no coincidence that this coincides with the fact that state constitutions are much easier to amend than the U.S. constitution.
Also, the appointment of state judges is less politically sensitive because a much smaller share of the state court docket than the federal court docket, deals with public law issues and constitutional rights. The state courts have relatively much less partisan deluges of debt collection actions, evictions, foreclosures, probate administrations, divorces, apolitical criminal cases, and mundane personal injury cases like slip and fall and car accident cases.
Why Are Constitutional Courts The Way That They Are?
Italy and most other countries with constitutional courts established them only after World War II, with much more historical experience to draw upon. And, the people who drafted constitutions with such courts envisioned those courts as expressly political, and so were conscious of the need to provide politically sensitive structures for them.
Judicial review of legislation for constitutionality is an American invention, and in the U.S., unlike most civil law countries with constitutional courts, it is a power shared by all judges, not just judges of the U.S. Supreme Court or a constitutional court. A municipal traffic judge can hold that a law is unconstitutional in the U.S., for example, and is required to do so if it clearly is unconstitutional.
In contrast, countries with constitutional courts don't have judicial review of the constitutionality of legislation and executive action by ordinary judges, so there is a concentration of political issues in a single court, making the necessity of political considerations more obvious.
Also, unlike the U.S. legal system, those countries handle issues of public law (i.e. the law of interactions with state entities by other state entities or individuals) in quasi-judicial bureaucracies distinct from the ordinary courts for the most part.
