Yes, a sitting US president can be sued in federal court, but only for actions taken outside of their official duties as president. This is based on a Supreme Court ruling in the case of Clinton v. Jones in 1997, which held that the president is not immune from civil litigation involving conduct that occurred before they took office or that is unrelated to their official duties as president.

However, it’s important to note that suing a sitting president is a complex legal process that involves many challenges, including questions of jurisdiction, standing, and separation of powers. In addition, a sitting president may have immunity from certain types of legal action or may be shielded from litigation by executive privilege.

It’s also worth noting that a president can be subject to impeachment by Congress for “high crimes and misdemeanors” committed while in office, which can lead to removal from office and potential criminal prosecution.

Several US presidents have been sued during or after their time in office. Here are a few notable examples:

Bill Clinton was sued by Paula Jones in 1994 for alleged sexual harassment that occurred while he was governor of Arkansas. The Supreme Court ruling in Clinton v. Jones allowed the case to proceed while Clinton was still in office, and he eventually settled with Jones for $850,000.

George W. Bush was sued in several high-profile cases related to his policies and actions while in office, including lawsuits related to the use of torture, warrantless wiretapping, and the Iraq War. Most of these cases were dismissed on various legal grounds, but some, such as Al-Aulaqi v. Obama, have been allowed to proceed in the courts.

Donald Trump faced numerous lawsuits during his presidency, including lawsuits related to his business dealings, his actions as president, and allegations of sexual misconduct. He was also sued by several states and advocacy groups over his policies on immigration and environmental regulations. Some of these cases were dismissed, while others are still ongoing.

It’s worth noting that lawsuits against presidents can be a contentious and complicated legal issue, and many cases are dismissed or settled out of court.