Lea Tsemel has been called a rebel with a lost cause and a whole lot worse. But as the intimate, powerful “Advocate” demonstrates, she lives up to the film’s title in the purest sense of the word: She stands up for people. It’s who she stands up for that causes all the controversy.

As a Jewish Israeli attorney who has tirelessly defended Palestinians who have turned to violence, Tsemel is a legitimate force of nature, and this examination of her and her career is potent enough to be shortlisted for this year’s documentary feature Oscar.

Expertly directed by Rachel Leah Jones and Philippe Bellaïche, “Advocate” examines Tsemel from numerous perspectives, delving into her history, her family and the way she operates day to day.

Radicalized by the aftermath of 1967’s Six Day War, Tsemel has been known for decades as the attorney not afraid to take on the really difficult cases. “It’s not that I like to,” she explains. “I’m not afraid to.”

More than that, no matter what the crime in question, Tsemel’s attitude is “I always see the person behind the case,” being both caring and concerned with the accused and their extended families.

And, as witnessed in a 1998 TV interview, Tsemel has long taken the measure of the still-unresolved Israeli-Palestinian situation.

“You should try to understand me,” she tells a disbelieving TV host. “I am the future. These will be issues for many years to come.”

Among the people Tsemel has defended, it turns out, is her husband, writer and activist Michael Warshawski, whom she did not cut any slack.

Intent on toughening him up during his imprisonment, she responded to his complaining by telling her spouse, “You are not worthy of being my husband,” a moment that had the desired effect.

Tsemel had some success defending Warshawski, and also was part of the legal team that won a landmark 1999 case when the Israeli Supreme Court banned violence in interrogations.

Mostly, though, as Tsemel is the first to admit, “We always lose,” and if “Advocate” does nothing else it underlines the ways the Israeli judicial system makes things difficult for Palestinian defendants.

“The fear is great on the part of the judges,” Tsemel explains. “Security is the dragon that stands guard.”

A commitment as fierce as this has an inevitable impact on the lawyer’s family.

While the lawyer’s daughter Talila enjoys the fact that her mother’s name is “like a magic spell that will save us,” it was different for her son Nissan.

Nissan had difficulty adjusting to the fact that his mother’s commitment to her clients often came ahead of her commitment to the family, recalling the moment she told him, “I can’t do anything else. I believe in it.”

The most gripping parts of “Advocate” are the film’s fly-on-the-wall cinéma vérité sequences of Tsemel at work, meeting with clients’ families, navigating the legal system and conferring about cases with fellow attorneys and her staff.

Tsemel’s cases are invariably tough ones, and among the defendants we watch her deal with are a man who stabbed an Israeli bus driver and 11 other individuals, and a woman depicted as a would-be suicide bomber who may have just been suicidal.

The most heart-rending case, and the one we follow from start to finish, is the story of Ahmad, a 13-year-old who chased people with a large, ornamental knife with the intention of scaring them but ended up being charged with attempted murder.

Among the quandaries Tsemel has to deal with is whether to plead Ahmad guilty to the attempted murder charge she knows is a fiction before the boy turns 14, in an attempt to get him a lighter sentence.

Perhaps the most remarkable thing about Tsemel is that, despite decades of cases not turning out the way she thinks they should, she is unbowed.

“I’m a very angry optimistic woman,” she says at one point, and what we see in this compelling film bears her out.