The whole concept just seems to just violate the independence of US courts.
(A key tenant of democracy)
Why would the founding fathers insert such a thing in the US constitution?
Your question is a great question, but the underlying premise is flawed. The courts are not independent. As the judicial branch of the US government, federal courts have a lot of leeway in addressing legal matters, but they do not do so apolitically. Federal judges are nominated by the President, and confirmed by the Senate. These judges are mostly nominated with an end goal in mind.
President Franklin Roosevelt, whose first wave of New Deal programs were resoundingly and repeatedly rejected by a conservative Supreme Court, nominated judges with an interpretation of the law that allowed for expansive federal action to solve the great problems of the day.
President Nixon, the first conservative to win an election in a generation (two if you don't count Eisenhower), sought out justices with more conservative perspectives. Given that modern conservatism was just taking shape (and still missing much of its religious and southern elements), it would be appropriate to view these appointees as social moderates.
President Bush, in light of the post 9/11 response, nominated justices sympathetic to the needs of a vulnerable and scared state seeking security.
Without going into detail and running afoul of the 20-year rule, President Obama's nominees, like the majority of democratic judicial nominees since FDR, interpret the Constitution to allow for an expansive government capable of tackling issues at all levels. President Trump has repeatedly made clear that his nominees have more restrictive interpretations of the Constitution.
With all that being said, the composition of federal courts in American history has varied greatly over time. Parties in power have always sought to balance the courts in their favor, and the modern era is ultimately no different. These nominees, as sympathetic to the political objectives of their party as their understandings of the Constitution have allowed for, have helped level the political playing field throughout that time.
Despite being politically-rooted, the Court has a long tradition of abstaining from ruling on partisan matters by citing a lack of jurisdiction (authority to hear to the case) or a lack of justiciability (ability to adequately resolve a problem). As a result, purely political issues (ex: gerrymandering) are left alone by the judiciary to be solved by the legislature or executive- at least until these issues cross some line in the legal sand and become fair game for the Court.
This seems, to be perfectly frank, an inefficient way to organize the judicial branch, ever teetering and tottering between ideologically opposed majority parties. It is, as a matter of fact, a check on political power, not dissimilar to the popular election of political leaders every few years. In planning a government that would prevent tyrannical rule, the Founding Fathers included inefficiencies like these to act as checks and balances between the different branches of government, on ambitious individuals, and on the federal government itself (via the States, the People, and the other branches).
Other checks and balances exist, too. Congressional confirmation of executive nominees, the ability of the Court to review and overturn laws, and even the power to pardon.
The pardon is not a power exclusive to the President, because pardoning is an ancient concept. This is, I believe, the root of your question and, despite my extensive diatribe, I can't give you much insight into the history of the pardon before the Constitution. I'd wager that the idea of a leader using a pardon for crimes pre-dates written history, so there's undoubtedly more to say on the subject.
I can tell you, however, that the Founders, drawing extensively from British law, modeled the executive pardon power on that of the King. Wary of the monarchy, they included specific limits. For instance, a President can only issue pardons for federal-level offenses. State governors are able to issue pardons for state-level offenses.
Because the Constitution has little to say on the subject, because the Court has rarely ruled on the power, and because the power hasn't been overly abused, the limits of the pardon are an unsettled legal matter. Theoretically, it might have been perfectly legal for Nixon to pardon himself after Watergate, but, as he was ultimately pardoned by Ford, no legal precedent on the matter was established.
I know this answer is very vague and roundabout, so I'm happy to answer to the best of my ability any follow up questions you may have .
This has been asked frequently recently, so these two links should be helpful:
And I recently answered something akin to extremely brief history of it with some highlights, opened to more specific follow-ups, and if I will not comfortable answering some due to being outside my scope ( like USA ), I will at least be able to point to some usable literature.
I will copy the answer here for convenience:
As the relevant question was already addressed, I will expand on the third paragraph of your remarks a bit. While if we characterize this, the practice of pardon ( or clemency, mercy, ... ) was standard and widespread, but it had significant opposition throughout the Middle Ages and Modern period, both in principle and in practice, on religious and secular grounds.
I should say to anyone interested in this subject, the royal prerogative of Mercy had, through its perceived misuse, a vital and quite decisive impact on English Revolution.
Various notions of the clemency can already be found in the code of Hamurabi, where we can see such examples if a married woman is seen with another man, the penalty is death by drowning, yet both of them can be acquitted merely through the husband´s forgiveness, so the King could issue a pardon.^(1) So as to avoid more contentious topics, ANE cultures, and specifically the Hebrew Bible, are also reach in dynamic relations between forgiveness and pardon between God and the Covenant, but this takes it outside its legal tradition, as the usual ANE law codes, including the chapters relevant from the Hebrew Bible ( Leviticus, Deuteronomy, ... ), were not actually used in legal settings. As this take still has some minor opposition, some literature below.^(2)
But, for example, one can find examples quite contrarian, that pardon was not in the domain of the sovereign/monarch, but citizens. After the Civil War ( ~ 403 BC ), one needed to go through a particular case of adeia, insofar as 6000 signatures of the petition were needed for a pardon in Athens.^(3)
By the time of Roman system, we get a much more intricate and nuanced picture with more specific applicability, and the dispenser of the power, earlier under the Senate, later Emperors. Venia was used under special circumstances either preceding the act ( age, sanity, ... ) or during the act. Abolitia was the erasure of the charge, which would also ensue if the accuser died or otherwise dropped the charges. But the term in Imperial Rome takes as that of an imperial act of clemency, usually paralleled with significant events, like jubilees, victories, and so forth.^(4)
We have this account from 1500 jubilee year, when a man from Hungary wrote a petition to papal court - Apostolic Penitentiary:^(5)
He had been staying in the house of Ágnes, the daughter of a local burgher named Mihály Szabó, when the woman’s husband surprised them. While escaping, he heard the husband threatening to kill his wife, whom he had caught in the act, so he turned back to save her […]. The husband then released her and attacked him, and he killed the husband in selfdefense. Ágnes was arrested and sentenced to death, but her release was procured and they clandestinely became betrothed; however, friends of the deceased husband, with whom Mihály was making a deal, made him swear that he would never marry her. As they hadn’t intended to kill the husband for the sake of their marriage, Mihály viewed the vow as detrimental and intended to have it revoked in order to enter into marriage with Ágnes. He beseeched the pope to absolve him from the crime of homicide and Ágnes from fornication, and to annul his oath.
The Tradition of Catholic Church was likewise influential, and the notion such as dispenza and rescript ( which goes back to the Roman legal system ) also expands to entail rescript of mercy, which would be issued directly by the Holy See, or from other local relevant ecclesiastical authorities, but merely in jurisdictions ( both geographical and legal ) as postulated in the law, and importantly, this mercy could be revoked.^(4)
Perhaps at this point I could answer this with a some particular examples.
Why was it created and what was it expected to be used for?
King Edward I. used the act of mercy as a recruitment during the times of war, for any trespasses ( murder, theft, ... ) in return for a year long service in without payment.^(6) Another one might be that during early modern period, in common law any act of killing was murder without exceptions, so to be exempt from it on whatever grounds, a pardon was needed. So in this sense, mercy supplemented the legal shortcomings.^(7)
To highlight one of those:
Pardon might also be contingent upon other circumstances: pregnant women were reprieved on the grounds that an innocent embryo should not pay the penalty for its mother's transgressions; in theory, they were to be hanged after the birth of the child, although it seems likely that most women who escaped hanging through 'benefit of the womb' were later fully pardoned. Some idea of the extent of the practice can be gained from the calculation that on the Home circuit of the assizes between 1558 and 1625, nearly half of the women convicted of felony claimed to be pregnant, and over a third (38 per cent) were successful in their claim.^(8)
And another significance would be that to both ecclesiastical and royal authorities, this brought quite a considerable amount of income.
As a curiosity, continental legal traditions, like German, where the prerogative of mercy or pardon was until the early modern period in the hands of the same tribunal or court that passed sentence. ( The remains of these traditions can be still seen in some countries, like Slovenia, as I am most familiar with it, where the request goes through the ministry of judiciary and the judge, who gathers the relevant facts about the case, and proceeds with recommendations and findings to the President, who can issue a pardon. )
Also, the act of pardon was abolished for a decade during the French Revolution, which is another nuanced and complex subject altogether.