Vanessa Lopez at the Philadelphia premiere of the film “14: Dred Scott, Wong Kim Ark & Vanessa Lopez.” (Roland Dahwen Wu/courtesy of Graham Street Productions)

Who is, or deserves to be, an American citizen is a simple question that gets complicated depending on what else is going on in the culture. Now that immigration is such a preoccupation for some, bills are periodically introduced in Congress to challenge the right of children born in the United States to undocumented immigrant parents to be considered citizens by birth. Check out the Birthright Citizenship Act of 2015 proposed by Rep. Steve King (R-Iowa).

Documentary filmmaker Anne Galisky, who has chronicled the immigrant-rights movement for years, takes on the question in a new work called “14: Dred Scott, Wong Kim Ark & Vanessa Lopez.” The film had its Washington premiere Thursday night at the E Street Cinema. Galisky is lining up more screenings in the area and hopes to pitch it to public television. “Talk to us about bringing it to your school, your nonprofit, your place of worship,” she said to the audience of 75 at the premiere.

Most people think they know all about Dred Scott, but they may never have heard of Wong Kim Ark or Vanessa Lopez. In its 1857 Dred Scott decision, the Supreme Court notoriously ruled that certain people born in the United States — African Americans — could not be considered citizens. The 14th Amendment, ratified after the Civil War, rebuked that logic: “All persons born or naturalized in the United States…are citizens of the United States….”

Wonk Kim Ark was born in 1873 in San Francisco to Chinese parents. He left the United States as a young adult, then tried to return. During a period of anti-Chinese fervor, American authorities sought to exclude him, reasoning that the 14th Amendment didn’t apply to the children of foreigners. The Supreme Court ruled in 1898 that Ark was an American citizen under the 14th Amendment.

At the time of filming, Vanessa Lopez is the 8-year-old American-born daughter of undocumented immigrant activist Rosario Lopez, now living in Seattle. Vanessa says she wants to be “either an artist, a photographer, a lawyer or a marine biologist.” With her unaccented English and her 8-year-old’s view of the world, she tries to puzzle through the thinking of adults who would deport her mother and grandparents and deny citizenship to children like her.

Vanessa serves as the heart-tugging emotional center of the film, while Galisky draws a direct narrative line from Scott to Ark to the Lopez family. Along the way, she interviews descendants of both Scott and Ark.

Galisky, whose previous film was “Papers: Stories of Undocumented Youth” (2009), said bills to undermine birthright citizenship may seem unlikely to pass, but “I think there’s danger even in calling birthright citizenship into question.”

In today’s context, a white woman with a name like Galisky might seem an unlikely candidate to be the daughter of a once-undocumented immigrant — but she is. Her grandfather and other relatives fled Stalin’s Russia to Mexico in the 1920s, where her father was born. They hired an American lawyer to help them immigrate legally to the United States in the 1930s, but he took their money and disappeared. The family came anyway, crossing the Rio Grande on horseback. Her father got a deportation notice after he graduated from high school. He responded by enlisting in the Army and serving during the Korean War. He became a legal resident afterward.

“I grew up with this story,” Galisky said. “I always knew I was a citizen because of where I was born.”