After walking out of a federal courthouse last month as free men, Nevada rancher Cliven Bundy and his sons apparently are eager to walk back in.

The Bundy camp has launched a legal offensive against federal and state authorities, filing three civil lawsuits in the last two weeks challenging public-lands policy in Nevada and alleging official misconduct in the 2016 Oregon standoff.

The spate of civil suits comes with the Bundys on something of a roll after twice thwarting federal prosecutors.

A federal judge on Jan. 8 threw out charges against Cliven Bundy, sons Ammon and Ryan Bundy, and Ryan Payne stemming from the 2014 Nevada standoff over prosecutorial misconduct.

In October 2016, a federal jury acquitted Ammon and Ryan Bundy and five co-defendants for their roles in the armed occupation of the Malheur National Wildlife Refuge near Burns, Oregon, which they described as a protest over federal-lands management.

Now Cliven Bundy wants to resolve his longstanding dispute over grazing rights with the federal government once and for all. His lawsuit filed Jan. 26 asks the court to declare that federal public lands representing 85 percent of the land within Nevada’s borders belong to the state.

Mr. Bundy has not paid federal grazing fees in order to avoid “giving money to an entity which does not actually own the land,” says the complaint, submitted in Clark County District Court.

Mr. Bundy has an urgent interest: He said the Gold Butte National Monument, created by President Obama in December 2016, overlaps with his family’s grazing land and threatens to shut down his cattle business.

“If left unchallenged, President Obama’s designation would preclude the Petitioner and The Bundy Ranch from continuing to function on the land, which it has used for at least 141 years, as well as disrupt the operations of The Bundy Ranch and destroy the Petitioner’s livelihood,” says the lawsuit.

In a separate matter, Jeanette Finicum filed a wrongful-death lawsuit on Jan. 25 over the killing of her husband, Robert “LaVoy” Finicum, a Bundy ally who was shot three times in the back in January 2016 by Oregon State Police at an FBI roadblock during the Malheur standoff.

The complaint, filed in U.S. District Court in Oregon, accused a slew of federal and state officials, including the FBI, the Bureau of Land Management, former Attorney General Loretta E. Lynch and Oregon Gov. Kate Brown of engaging in a conspiracy against Mr. Finicum.

A Deschutes County Sheriff’s Office investigation concluded the shooting was justified, saying that the 54-year-old Finicum appeared to be reaching into his jacket, where he kept a 9 mm handgun. But the lawsuit alleges he was targeted for his political and religious beliefs.

“These defendants were mentally predisposed and committed to using excessive lethal force, to solve a political dispute,” says the filing, which seeks millions in damages. “The result has been both haunting and tragic.”

Mrs. Finicum has long discussed the possibility of a lawsuit, but her case recently was bolstered by two events: the June indictment of FBI agent W. Joseph Astarita for lying about firing his weapon and the release in December of a scathing BLM memo.

That document, written by BLM investigator Larry Wooten, accused the bureau of “extreme unprofessional bias” in its handling of the 2014 standoff at the Bundy ranch near Bunkerville, Nevada, as well as “clear prejudice” against the Bundys and their supporters.

The memo also said that BLM agents displayed antipathy toward Mormons. The Bundys are members of the Church of Jesus Christ of Latter-day Saints, as was Robert Finicum.

In a court filing Friday in the Astarita case, federal prosecutors said that Oregon SWAT officers did not wear body cameras at the scene at the request of the FBI.

The four passengers in the Dodge truck driven by Finicum — Ryan Bundy, Shawn Cox, Ryan Payne and Victoria Sharp — have also sued, accusing a host of state and federal officials of conspiracy, negligence, assault and battery.

Finicum sped past the first police stop before driving onto the shoulder at the roadblock on Highway 395. After he was shot, authorities pelted the car with flash bangs and sponge projectiles with pepper spray to “disorient any other armed occupants,” according to the FBI.

The complaint alleges that officers shot at the car.

“Laser lights are all over inside the truck and the passengers sitting like ducks in a barrel and knowing at any second the next bullet will be their demise,” says the complaint.

Ryan Bundy was treated for a shoulder wound afterward and has said he was shot, but so far he has not allowed the metal fragment to be removed, saying he wants to preserve it as evidence.

“There’s a bullet in there,” Mr. Bundy told The Oregonian, which published X-rays of his shoulder. “I can see what it is. It’s shaped like a bullet.”

The four passengers, who are representing themselves without the help of attorneys, named Mr. Astarita, FBI special agent in charge Greg Bretzing, Ms. Brown, and a man identified as an FBI informant, among others.

The lawsuit seeks millions in damages as well as a ruling that the defendants can never hold public office again “as they have held their offices in Bad Behavior.”