Donald Trump hit the campaign trail again last weekend, and he certainly seemed happy to be back in the spotlight. He bashed President Biden and undocumented immigrants, repeated his false claims of a stolen 2020 election, and hinted at a possible run for the presidency again in 2024.

But as he contemplates a return to politics, he has a more immediate question to contend with: Will he be able to stay out of legal trouble?

On Thursday, the Manhattan district attorney’s office charged the former president’s real estate company, the Trump Organization, with running a 15-year scheme to help executives avoid taxation. A top Trump lawyer, Allen Weisselberg, was accused of dodging taxes on $1.7 million in income; he surrendered to the D.A.’s office on Thursday morning.

Mr. Weisselberg’s was the first indictment to come out of a lengthy investigation that is being conducted by that office, and it could signal a turning point. If he agrees to testify against the former president, Mr. Weisselberg would be a powerful witness: He has long been one of Mr. Trump’s closest financial advisers, and Mr. Trump once praised him for his willingness to do “whatever was necessary to protect the bottom line.”

After the Jan. 6 attack on the Capitol, Mr. Trump was impeached for a second time — something that hadn’t happened to any previous U.S. president. If he were to be indicted on a criminal charge, that too would be a first for a former president.

Ed Rollins, the chairman of the Great America PAC, which backed Mr. Trump’s 2016 and 2020 campaigns but has not pledged to support him in 2024, said that Mr. Trump remained the presumptive front-runner for the Republican nomination. Still, he said in an interview, the threat of criminal prosecution “certainly makes it more difficult” for Mr. Trump to claim the party’s mantle.

“You have to be adding people, adding players, convincing people that, ‘My loss was detrimental to the country,’” Mr. Rollins added. “People are going to be saying: ‘Tell me why I should go back to you. Why should I put money into your campaign?’”

And the Manhattan D.A.’s investigation is only one of a smattering of legal obstacles that Mr. Trump may need to overcome, as he considers a possible return. Here’s a look at the many investigations and lawsuits that he’s currently fighting — touching on his business dealings, accusations of misconduct toward women, and his role in drumming up the Capitol riot.

Taxes and financial affairs

Mr. Weisselberg was indicted as part of a long-running investigation by Cyrus Vance, the district attorney for Manhattan. At Mr. Weisselberg’s arraignment on Thursday afternoon, prosecutors described a 15-year tax fraud scheme and leveled 15 felony counts against him, the Trump Organization and Trump Payroll Corporation.

Mr. Vance has assembled a grand jury and is in the process of determining whether to bring charges against Mr. Trump; the body has already questioned a number of the former president’s associates. Prosecutors have seized Mr. Weisselberg’s personal tax and financial records, as well as those of his daughter-in-law.

Letitia James, the New York attorney general, also opened a parallel investigation into whether the Trump Organization had manipulated property values to avoid taxes and gain other financial benefits. In May, Ms. James’s office announced that its investigation, which began as a civil concern, had expanded into the criminal realm and would join Mr. Vance’s inquiry.

The former president’s niece, the psychiatrist and author Mary Trump, has also sued him for fraud. Last year, she filed a suit claiming that Mr. Trump had defrauded her out of tens of millions of dollars. She had claimed that when her father, Fred Trump Jr., died, she was prevented from accessing her stake in his will, and that her share was slowly depleted by Donald Trump and other family members. After Fred Trump Sr. died, the remaining Trump siblings sought to exclude Mary from the family holdings entirely, she said.

She accepted a settlement in 2001, but after a 2018 Times investigation drew back the curtain on the family’s finances, she filed a lawsuit accusing her uncle and his siblings of fraud and breaching fiduciary trust. The suit is still pending.

Defamation claims

The most high-profile lawsuit against Donald Trump may be the one brought by E. Jean Carroll, a journalist and advice columnist, whose 2019 book accuses him of raping her in the 1990s. After Mr. Trump publicly denied the allegation and said Ms. Carroll was “not my type,” she sued him for damaging her reputation and career.

When Mr. Trump was still in office, the Justice Department sought to stanch the lawsuit by arguing that he was legally protected from defamation suits filed over things he said while executing his duties as president. A federal judge ruled against the administration, but the agency’s lawyers appealed.

Under Attorney General Merrick B. Garland, Biden’s Justice Department has continued the appeal, saying that Mr. Trump’s remarks should be protected under the Federal Tort Claims Act.

Another woman, Summer Zervos, sued Mr. Trump in 2017, days before he took office, saying that he had damaged her reputation and her financial well-being when he denied her accusation of sexual assault. The dispute stems from her time as a contestant on “The Apprentice,” when she claims he groped and kissed her against her will.

Because he made the statement in question before becoming president, Mr. Trump’s remarks aren’t protected under the Federal Tort Claims Act. The suit is currently before the New York Court of Appeals.

His actions on Jan. 6

Members of Congress and Capitol Police officers have filed separate suits seeking to hold Mr. Trump accountable for his role in organizing and riling up the rioters who stormed the government building on Jan. 6.

Representatives Bennie Thompson of Mississippi and Eric Swalwell of California, both Democrats, have both filed suits arguing that Mr. Trump violated the so-called Ku Klux Klan Act, a Reconstruction-era law that makes it a crime for people to conspire to prevent elected officials from discharging their duties.

In a different suit, a pair of Capitol Police officers who were injured on Jan. 6 are seeking damages from Mr. Trump for his part in the events of that day. The officers, James Blassingame and Sidney Hemby, say in the suit that they were hit with bear spray, assaulted with flagpoles and crushed against a door by the attackers as they tried to fight them back.

The attorney general of Washington, D.C., Karl Racine, has also opened an investigation into whether Mr. Trump’s incendiary language rose to the level of criminal incitement.