the 20th century, although some attribute the militarization to the more recent campaigns on drugs and terror. Historian Charles Beard argued that cultural change during the Great Depression encouraged the militarization of law enforcement, whereas Harwood argues that the creation of Special Response Teams and tactical units within law enforcement during the 1960s began such a trend. Beginning in the 1990s, the use of military equipment and tactics for community policing and for public order policing has become more widespread under the 1033 program. The program prompted discussion among lawmakers in 2014 after unrest in Ferguson, Missouri. President Obama introduced restrictions in 2015 on the transfer of surplus military equipment to police. In 2017, the Trump administration announced it would reinstate the program. No-knock warrants The use of no-knock warrants has become widespread and controversial. Their use has led to misconduct, unlawful arrests, and deaths. Qualified immunity The U.S. Supreme Court first introduced the qualified immunity doctrine in 1967, originally with the rationale of protecting law enforcement officials from frivolous lawsuits and financial liability in cases where they acted in good faith in unclear legal situations. Starting around 2005, courts increasingly applied the doctrine to cases involving the use of excessive or deadly force by police, leading to widespread criticism that it, in the words of a 2020 Reuters report, "has become a nearly failsafe tool to let police brutality go unpunished and deny victims their constitutional rights". Warren v. District of Columbia In the 1981 case Warren v. District of Columbia, the ultimate ruling was that United States law did not require law enforcement officers to protect the general population, that ordinary citizens could not be classified as persons requiring special protection, and the officers had no legal duty to protect. This and other cases have been used to establish legal precedents in many jurisdictions across the United States. Such precedents are often used to protect law enforcement officers and organizations from being charged with inaction during riots or mass shootings. Civil asset forfeiture Rules on civil asset forfeiture allow law enforcement officers to seize anything which they can plausibly claim was the proceeds of a crime. The property-owner need not be convicted of that crime; if officers find drugs in a house, they can take cash from the house and possibly the house itself. Commentators have said these rules provide an incentive for law enforcement officers to focus