Question: Is there a historical explanation as to why the USA people are so litigious compared to France?...............

Extremely Short Answer: Courts in the US have simple put always played a more prominent role in governance. Simple sounding court cases sometimes are among the greatest sources of change and accountability in the US political system. Thus Americans are more litigious because it's the way the government was designed, courts play historically a more prominent role in the us political system as a not just independent organization but a fully equal branch of government with the legislature and presidency.

Short Answer:
Both France and the United States are Republics but their forms of republics are organized entirely differently.

In France judiciary checks on government are historically seen negatively as a obstacles to popular sovereignty. France's Conseil Constitutionnel which rules on constitutional law has historically been "obscure and insignificant institution".

• it only became a resource for the courts in challenging laws “constitutionality” in 2008 constitutional amendment.

Similarly France's Constitutionally empowered high court responsible for ruling on governmental abuse of power and corruption of public officials, has never been called into session. Rather France has utilized lower courts or the presidentially empowered Cour de Justice de la République created in 1993, for this purpose. Because France historically trusts in its elections to regulate abuses and hold their leadership to account and has traditionally chosen not to empower appointed judges over elected politicians until relatively recently.

In the United States, popular sovereignty has never been the objective. Originally the people only voted directly for 1/6th of the government. The House was the only elected body. Governance in the US has been much more concerned with checking and curbing the authority of elected officials especially those in the majority, at the expense of popular sovereignty. Popular sovereignty in the US has become more important but is still more strictly regulated. Maintaining the status quo even over the objections of the majority is much more emphasized.

Historically I would propose this has to do with the nature of threats the two states have faced. France has faced existential threats from external sources throughout it's history and thus values decisive majorities empowered to act in the countries interest. The United States founding fathers, without a substantive external existential threat, were more concerned with internal abuses of power subverting the republic. The American founding fathers formed a government which relies more on the Judiciary as a co-equal branch of government with the legislature and Executive, with each of the 3 branches regularly applying checks and balances on the other two. The net effect often being stalemate.

The result is the judiciary plays a much larger role in keeping the American government responsive and on track, sometimes it just plays a larger role.

Culturally in the United States, litigious individuals result in some of the greatest change in the American Republic and laws and regularly trump Presidents and even legislative majorities. Court cases as obscure as the selling or not selling Cakes, sitting in the front of a bus, or when a low budget movie can be released relative to an election have resulted in cataclysmic changes in the American government and political system. Likely because in the United States, appointed judges and courts have often been a reliable avenue to change when elected officials have refused to act. In the United States this is not seen negatively, but is by design. It's written into the Constitution, the courts role in governance.

More Detailed Answer:

Different forms of a Republic
A Parliamentary form of government like France is fundamentally organized to empower democratically elected majority to govern. The party with the most legislative seats is invited to form the executive. They recommend the ministers or cabinet secretaries. Thus every Parliamentary executive / Prime Minister enjoys significant support in the legislature by definition. Alternatively in America the founding fathers were more concerned with the abuses of government than they were motivated by responsive governance. The United States is not organized to promote the authority and power of the majority but to control and frustrate that power. Organized with three branches of government each with oversight of the other branches. With it's two party system it's a rare event when one party controls all three branches of government, and it's much more common for one branch of government to completely block the government as a whole from accomplishing anything over the objections of the majority of the population. Checks and balances. It is a system of government fundamentally organized to form gridlock; empower minority, and to thwart the ambitions of the majority.

The Role of Courts in the US
Unlike in France, In the United States the courts are not just empowered to be independent but they are fully a coequal branch of government with the Executive(Presidency) and the legislature. Thus many important governmental policies which could not pass into law in the other two branches of government ( due to political or popular opposition) become defacto law through court cases. "reinterpretation" of existing laws to create new laws..

Examples...

Judicial activism

• Brown v. Board of Education – 1954 Supreme Court ruling ordering the desegregation of public schools.
• Roe v. Wade - 1973 Supreme Court ruling creating the constitutional right to an abortion.
• Bush v. Gore – The United States Supreme Court case between the major-party candidates in the 2000 presidential election, George W. Bush and Al Gore. The justices voted 5–4 to halt the recount of ballots in Florida and, as a result, George Bush was chosen as president.
• Citizens United v. Federal Election Commission – 2010 Supreme Court decision declaring Congressionally enacted limitations on corporate political spending and transparency as unconstitutional restrictions on free speech.
• Hollingsworth v. Perry – 2013 decision by federal judge Vaughn R. Walker overturning California's constitutional amendment to ban same-sex marriage.
• Obergefell v. Hodges – 2015 Supreme Court decision declaring same-sex marriage as a right guaranteed under the Due Process Clause and the Fourteenth Amendment

In France you have a High court to rule on governmental abuses. Also in France that high court has never been called into session since the passing of the current constitution in 1958. Likewise France has a Conseil Constitutionnel to rule on the constitutionality of laws, which historically is an "obscure and insignificant institution". That is changing but the relatively underused institutions relative to the US Supreme court is probable a reflection of Frances smaller concern with judicial oversight and smaller paranoia of abuse of power by elected officials who after all stand for reelection and are more accountable to popular elections.

This is not the case in the United States. In the United States the Supreme court regularly hears cases which impose restrictions, repeal laws, even stands up to majority held positions and has since the early days of the republic.

Thus being litigious in the United States is a way change governmental policies even participate in the political system, regardless of political support or popularity of your position. (at least in theory).

Question: (With Regards to Americans being more litigious)..Is it because the country is, in some way, still "young" with way fewer laws (I have no idea if this is actually the case)? Or is it something else?

France culturally and historically is a much older country than the United States; however neither the age of it's Constitution nor it's years as a Republic exceed the United States. The United States has been a Republic longer than France and the American Constitution ratified June 21, 1788 predates the French constitution (ratified in 1958) by nearly two centuries. In fact the United States has arguable one of the oldest Constitutions in the World which is still in use.

• Ten Oldest Constitutions has the United States Constitution oldest
• Politifact "As a single document laying out an overall framework for governing a country -- a common way many people would define a constitution -- the U.S. truly has the oldest one still working. We rate the claim True"
• Lists of National Constitutions has the United States Constitution as the oldest.

Question: In France, a lawsuit takes a very long time (years) and cost a lot of money (without much gain to win) which isn't the case in the USA. But what brings these differences in the first place?.................

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Actually it's not uncommon for lawsuits depending upon subject and scope to take years even decades and cost millions of dollars in the United States also. This is still often times the most efficient way to cause change in the US given political realities.

In 2017 the Washington Redskins American football team won a court case which tried to vacate the teams trademark on it's name. The court case was first begun 25 years ago, and folks who brought the case were still pursuing appeals.

• Washington Redskins win trademark fight over the team’s name

Comments

@Denis de Bernardy
... Characterizing France's Conseil Constitutionnel as an "obscure and insignificant institution" is dubious. It's not easy (or wasn't until 2010 anyway)

That statement "obscure and insignificant institution" historically, is a direct quote from the given source....

Judicial Activism in Comparative Perspective pp 133-154

My belief in characterizing France's Conseil Constitutionnel as insignificant institution historically speaking is because since Frances constitution was ratified in 1958 up through the first few decades, the Conseil was primarily used by the President against Parliament and was unreachable by France's Courts. Thus it wasn't really a resource on ruling laws Constitutional or not but a resource by the Executive to keep Parliament from infringing on it's authority. The Conseil Constitutionnel was sometime called the "President's cannon" or "a cannon pointed at Parliament" because of 21 cases brought before it prior to the mid 1970's 20 were brought by the President against Parliament. It wasn't until the French Constitution was amended in 2008, that the Council was even permitted to hear cases refereed to it from France's lower courts on questions of unconstitutionality of laws. Even then those cases did not take the form of formal hearings but lower courts submitting questions as to the constitutionality of laws.

I would agree with you however that the Conseil Constitutionnel does play a much more prominent role today, just not historically... this is a reflection of France's traditionally has been less willing to allow appointed judges to overturn their elected officials. It's a much more recent evolution in France for the judiciary, while in the United States the Supreme court has been doing just that for hundreds of years.

@Denis de Bernardy Also, France has two high courts, not one. The Cour d'Etat is the high court for public law, in addition to advising the Executive branch. The Cour de Cassassion is the high court for private law. The Cour de Justice de la République is a Special Court that sits when high office holders get impeached. –

Yes Agreed, and their is overlap between the courts too, as other courts can hear cases involving abuse of power, not just the Justice de la Republique.

But my point is the Justice de la Republique was created in 1993 by the French President to deal with a imminent crisis(aids tainted blood supply crisis). The 1958 constitution allows for an independent High Court to rule on governmental mis conduct. Only that Court has "never-as-yet-convened" and again I cite this to demonstrate France's historic resistance in having appointed judges ruling over their elected officials.

I don't argue that this resistance has changed, or that such courts don't today rule and act on constitutional issues. My point was in the US this process is nearly as old as the constitution and the supreme court as a co-equal branch of government was always envisioned to provide checks on congress and the presidency. In France this is a much more recent thing and reflects a different attitude on government and popular sovereignty.

@DenisdeBernardy Also, I'm not sure I agree with your assessment that France's constitution is built with the idea of handing the reigns of power to the majority.

I can see your point. But relative to the American System of government with it's independent Presidency, Parliamentary systems where the Executive is almost always controlled by the party which controls the majority in the legislature is by definition empowering the majority. The Prime minister must enjoy the support of the majority of the Parliament to fend off a vote of no confidence. Loss of a simple majority vote topple the government. I agree with you relative to the second and third republics one would not make the same claim about the 4th republic empowering the majority. But the original question draws us to compare the US and French systems, or at least my answer to the question does. For that comparison the statement is valid.

This is a difference but not a criticism as I would note that Parliamentary systems of government are much more efficient and are much more organized to get things done; where the American form of government is really geared to create stagnation and frustrate the majority. Perhaps something only the most cynical electorate would support. Which again probable accurately describes the American founding fathers with regards to governments.

While this isn't exactly a historical answer, it does provide a reasonable part of an explanation:

Different people pay the costs in a lawsuit in the USA and France

In France, the legal costs are paid by the losing side in most lawsuits (the so-called English Rule). The reasoning behind this is that a litigant (whether they bring or defend the claim) is entitled to legal representation and and, if successful, should not lose any money because they defended themselves. This means that people are less likely to start frivolous lawsuits because if they're found to be the loser, they end up paying a lot of money.

In the USA, each side is responsible for their own legal fees in most lawsuits(the so-called American Rule). The reasoning behind this is that people should not be afraid to start a lawsuit because of the costs if they end up losing the lawsuit, because a judicial verdict can provide a meaningful extension of the coverage of the law.

The legal systems in France and the USA are different

France uses the Civil Law system, the most common system in continental Europe which dates back to the Roman Era. This system is based around establishing in advance whether something is legal or not, and lawsuits are intended to decide whether a specific law has been broken or not. Generally speaking judges aren't really expanding on the law and are instead focused on finding out the truth: who did what to whom and why?

On the other hand, the USA uses the Common Law system, which is named that way because it was the "common" system of law across most of Feudal England. Common law is mainly in use in countries that used to belong to the British Empire. A large focus of Common law is the idea that the court has a large impact on legal doctrine: A lot of times, the law itself is quite vague, and any judge can make his own judgment of how to apply a law to a given case, with the most important result being that this judgment essentially becomes a new law that can pretty much only be overruled by a higher court of law. This is called Precedent and is the cornerstone of Common Law. Because of this, people are again more inclined to start new legal cases, because chances are that they could completely change a significant section of the US legal code, even to the point of changing how laws dating back to the very beginning of the nation should be applied to modern hot topics like abortion, gun control, LGBTQ rights and many other topics on which the nation is highly divided.

Very little scholarly work has apparently been done on this, so my answer will closely follow the article "The Culture of Tort Law in France" by Jean-Sébastien Borghetti (2012).

The question here reflects a strong perception that lawsuits are far less common in France, which is only partly accurate. Tort law does play an important role in France, although somewhat less important than other countries. Both this underlying fact and the exaggerated perception of it can be explained historically.

One key point is that other kinds of compensating institutions are strong in France like social security benefits, special state compensation funds (like that for asbestos victims) and private direct insurance. These alternatives are not available as readily in the United States, so victims are forced to turn to lawsuits.

Perhaps ironically, reliance on other institutions seems to result from a strongly pro-victim orientation in French tort law. Borghetti suggests that judges are often hesitant to let lawsuits move forward precisely because the system is so slanted in favor of the victim. Regarding the original academic legal philosophy that produces this situation, Borghetti emphasizes its historical development:

this orientation is now quite old, and can be traced back at least to the end of the 19th century when various authors began to contend that the courts should not stick to liability for fault, as laid down in the code civil, but should instead create categories of no-fault liability, even without the legislator’s permission, in order to help compensate victims of industrial accidents. At that time, the political convictions of left-wing lawyers appeared to merge with the Christian concern for the poor and the afflicted.

The greater prevalence in France of private insurance specifically also helps to explain the perception that lawsuits are less common. Most lawsuits in France happen "behind the scenes", handled by the insurance companies on both sides. Someone who is wronged in France may get paid without ever knowing their insurance company sued or settled. Similarly for the party that caused the harm, they may not know their insurance company paid out to the victim. As a result, media coverage of major lawsuits also tends to be less prominent in France, because while tort law does play an important role in the legal system, it is just not something everyday people have the same awareness about in their own experience.

EDIT: Comments by @fredsbend and @JMS both question the relevance of Borghetti's point about social security benefits. I think it is fair to question this point. Here's a key paragraph from the article I tried to summarize here.

French social security, first of all, is rightly known for being relatively well-developed. Despite efforts by the Government to curb the steady rise in the system’s budget, the medical branch still offers generous coverage in respect of most health costs that may be incurred by individuals. This is especially true for serious medical treatment which may typically follow an accident. When the patient is prevented from working due to his illness or accident, the social security system will compensate for lost income up to a fixed amount. The result is that most victims of physical injury in France will receive at least partial compensation, through social security, for the financial loss resulting from their injury. As a consequence, compensation through tort law does not usually play the vital role that it does in other legal systems where this type of compensation may be the only means for victims of personal injury, who do not benefit from social security or health care coverage, to fund adequate medical treatment and stay financially afloat.

Although Borghetti does not provide much data, I do find these assertions plausible. For example, look at the very different relationship between medical costs and personal bankruptcies in the United States versus France.