The two tech titans have accused each other of copying such familiar functions — and they’re set to duke it out this month as they begin yet another round in a long-running legal war that has spanned nearly three years and four continents.

It’s a seemingly endless battle — and one that has begun to capture Washington’s attention. President Barack Obama and key lawmakers are backing new patent reforms, saying companies are too often forced to spend money on costly litigation rather than new, innovative research. And the Supreme Court is due to take up a case this month that could upend many high-profile patent lawsuits in the tech industry.

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But there may be limits to D.C.’s actions. Congress has so far focused on curbing “patent trolls” — firms that amass patents solely to sue other businesses — not high-profile corporate lawsuits. And if the Supreme Court takes a narrow legal perspective, it may not make much of a ripple in the litigation landscape.

Nearly all of the major smartphone makers have sued or been sued by competitors in recent years, often over seemingly small technological details. The companies are trying to get a leg up over rivals in the fast-growing global smartphone market, which is today estimated at $300 billion. Apple and Samsung have sued each other more than 40 times, and they’re headed back to court in California on March 31.

“It’s just culturally unacceptable to either organization to think about settling, so they’re going to continue to battle in the courts,” said Van Baker, a mobile technology analyst at Gartner. “They’re bitter rivals in the smartphone space, and that’s not going to change anytime soon. Any little competitive win or advantage is important.”

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Samsung declined to comment for this story, and Apple didn’t return a request for comment.

Apple has long targeted iPhone copycats. Its late CEO, Steve Jobs, famously vowed to wage “thermonuclear war” against companies he felt ripped off the device — particularly Google, which makes the Android mobile operating system. Apple has gone head to head with Samsung, HTC and Motorola, all of which make Android-based phones.

The Cupertino, Calif.-company brought its first case against Samsung in 2011, claiming Samsung copied iPhone and iPad features like pinching to zoom on the screen and the size and shape of the device. After appeal and retrial, Apple was awarded $929 million in damages but lost its request for a U.S. sales ban on 23 older Samsung devices. Both companies have now appealed parts of that case.

The latest Apple suit alleges that newer Samsung devices such as the Galaxy S3 phone infringe Apple patents on slide-to-unlock and other features. Samsung filed a countersuit centering on its patents for 4G wireless technology — which it says the iPhone 5 and other Apple products violate. That case will head to jury trial at the end of the month in U.S. District Court for the Northern District of California.

There’s a growing sense in Washington that patent lawsuits are a drain on the economy and a symptom of a dysfunctional patent system. Critics say the U.S. Patent and Trademark Office has approved too many vaguely worded, low-quality patents, especially in the software industry.

The White House and lawmakers have coalesced around an effort to crack down on patent trolls, which are widely accused of preying on businesses. But troll lawsuits are just one piece of the patent litigation picture — and the leading congressional bills, as currently written, wouldn’t do much to discourage big companies from suing each other.

One proposal up in the Senate has the potential to reduce cases like Apple vs. Samsung, but it’s been a hard sell. It would expand a program letting companies go to the USPTO, instead of the courts, to invalidate bad patents — including software patents at the heart of much of today’s litigation.

Thanks in large part to lobbying efforts of groups representing Apple, Microsoft and IBM, however, the review program was dropped from the House patent bill before it passed the lower chamber late last year. And a bill from Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.) — headed for a markup in early April — so far doesn’t include anything on the review program.

In many ways, the corporate patent wars and the troll problems are two sides of the same coin, as both stem from the granting of overly broad patents, said Robin Feldman, a professor at the University of California Hastings College of Law.

“These broad software patents make spectacular weapons,” Feldman said. Lawmakers’ “short-term” approach to the issue — making it harder for trolls to sue businesses — might reduce some patent litigation but won’t stop it because it doesn’t get at the underlying problem, she said.

The Supreme Court will have its own chance to weigh in. On March 31, the same day Apple and Samsung open a new round in their legal war, the high court will hear oral arguments in a case that could set the standards for patenting software. If the court makes an expansive decision, some of the broader patents at the center of the battle between Apple and Samsung could be rendered ineligible.

Nearly every major tech company is closely following the case, and many have filed briefs staking out their positions. Apple, in its filing, urged the court not to invalidate all software patents. Google, along with companies like Twitter and Amazon.com, pressured the court to make it easier to eliminate bad patents.

Not everyone sees the smartphone wars as a sign of a broken patent system — or thinks Congress should fix it. Rather, they say the thicket of court cases proves the system’s value.

“[The smartphone cases] show that the patent system has validity — it’s important,” said Todd Dickinson, a former PTO director who now heads the American Intellectual Property Law Association. “It’s being used to try to protect the investment these companies have made, and their shareholders have made, in the research that leads to these phones.”

Dickinson says the patent battles will eventually work themselves out through licensing or cross-licensing deals. The introduction of the sewing machine, the automobile and even the computer led to a similar onslaught of legal showdowns — all of which were eventually resolved through the existing system, he said.

Reformers and critics don’t expect the Apple-Samsung duel — or smartphone litigation between other companies — to end overnight.

“The patent system in recent years has been like the Wild West with no sheriff in sight,” Feldman said. Without congressional reform or a Supreme Court decision, she said, “we’ll continue on the destructive path we’ve been seeing for some time.”