Generate an appropriate single-sentence summary for the given text such that it includes the main topic of the text.
One example is below.
Q: By Marianna SpringSpecialist disinformation reporter, BBC News The adverts show the Democratic Party challenger with an earpiece, and say that he refused to have his ears checked for devices prior to the debate. The Biden campaign rejected the claims. The Trump campaign adverts ask: "Why won't Sleepy Joe commit to an ear test?" and "Who is in Joe's ear?" Accusations that presidential candidates have received debate help via hidden hearing devices are familiar, albeit unproven. Such allegations have been levelled against both Republican and Democratic candidates in the past. Prior to Tuesday's debate, the rumour about Mr Biden's supposed earpiece was circulating on several social networks, and was being promoted by the Trump campaign. At least 15 versions The advertising campaign was launched after the debate, and also promotes two other baseless but widely shared rumours about Mr Biden. One suggested he asked for breaks during the debate, and another accused him of refusing a "drug test". The photo featured in the advert is not from Tuesday's debate. It was first shared online in September 2019. In a number of the adverts, it has been doctored to show Mr Biden wearing wireless Apple headphones. This was not the case in the original image. Some versions circle the ear featuring the headphone. By Wednesday evening, there were at least 15 different versions of the advert, and according to Facebook's Ad Library, they had reached at least 10 million users. Facebook has pledged to label posts containing voting misinformation and point users towards accurate information ahead of the election. However its policy does not involve fact-checking political speech, including in advertisements. The company declined to comment about the latest Trump ad campaign. Rumour origins Hours before the debate, the claims went viral on Facebook and YouTube. Identical memes were pushed by a number of popular Facebook pages with names such as US Conservative and Unhinged Left. They claimed "Joe Biden should be inspected for a hidden earpiece as well as submit to a drug test before the debate". These memes are subject to fact-checks - and some have had warning labels applied to them on Facebook. The claims were picked up by Fox News and other conservative news outlets. They were further amplified by supporters of QAnon, an unfounded a conspiracy theory that claims President Trump is fighting a secret war against elite Satan-worshipping paedophiles. Those who believe in QAnon are known for promoting political disinformation on social media which targets opponents of the president. They shared close-up pictures of Mr Biden's ears, alleging a listening device was visible. During the debate, some also shared photos of a fold in Mr Biden's shirt, claiming it was caused by a wire, and of a supposed device on his wrist, where he wears a rosary in memory of his late son Beau. Nothing new Conspiracy theories about secret listening devices have been recycled in presidential election campaigns for the past two decades. Democratic candidate Hillary Clinton faced similar unfounded claims ahead of the 2016 presidential election. In 2004, rumours circulated among left-wing sites and blogs that President George W Bush was being aided by a secret earpiece. None of those allegations were found to be true. Even if a candidate did wear an earpiece, any advantage would be questionable. As TV and radio presenters can attest, listening to someone while simultaneously talking during the back-and-forth of a live event is a difficult skill to master.
A: US President Donald Trump's re-election campaign is running hundreds of Facebook advertisements pushing an unfounded conspiracy theory that Joe Biden cheated during the first US presidential debate.
Rationale: This is a relevant summary for the given paragraph. It also contains explicit phrases from the given text
Q: Francisco Sanchez, 45, was charged on Monday with shooting 32-year-old Kathryn Steinle on Pier 14 in San Francisco. Mr Sanchez, a repeat drug offender who has been deported to Mexico five times, had been in jail in the city until March when the charges were dropped and he was released. But despite being in the country illegally, he wasn't handed over to immigration officials because San Francisco's "sanctuary" law means city authorities don't co-operate with immigration officials. So what is a sanctuary city? The term applies to cities in the US that have policies in place to limit the assistance given to federal immigration authorities. It's not a legal term so the way it is implemented can vary, but the policies can be set in law or just part of local policing practices. San Francisco passed a "City of Refuge" order in 1989 that prohibited the use of city funds to enforce federal immigration laws or to share information with federal immigration officials. In the case of Francisco Sanchez, this meant that when the US Immigration and Customs Enforcement agency (ICE) asked to be notified prior to his release from prison, their request was ignored. In March, ICE Director Sarah Saldana told Congress there were over 200 areas in the US - cities, counties and states - that had refused to honour the agency's requests. Why do they exist? The idea of declaring areas as immigrant sanctuaries got traction in the 1980s after Los Angeles told its police force to stop questioning people solely to determine their immigration status in 1979. LA authorities put the order in place in a bid to encourage immigrant communities to work with police without having to fear being deported. Other cities that followed suit argued that implementing government policy wasn't their job and doing so threatened community relations. So what's the problem? Opponents of sanctuary cities have long accused them of undermining federal law enforcement efforts and encouraging illegal immigration - and Francisco Sanchez has intensified criticism. To make matters worse for San Francisco, Mr Sanchez reportedly told police he had chosen the city precisely because he would not be pursued by immigration officials there. Critics of sanctuary policies have leapt on his case. Outspoken Fox News presenter Bill O'Reilly said Miss Steinle paid for the city's "irresponsible and unconstitutional decision with her life". What does San Francisco say? Despite the criticism, San Francisco Sheriff Ross Mirkarimi stands by the decision to ignore the ICE request and insists the sanctuary status makes the city safer. "We're a world-renowned city with a large immigrant population. From a law enforcement perspective, we want to build trust with that population and our sanctuary city laws have allowed us to do that," he told CNN. He claims ICE's system of requests - called "detainers" - is not legal and says they should have issued an arrest warrant for Mr Sanchez if they thought he was a threat. What's this got to do with Donald Trump? Billionaire businessman Donald Trump is keen to make immigration a key part of his campaign to become the Republican presidential candidate. Speaking at his campaign's launch event, he claimed that Mexico was "sending people that have lots of problems", adding: "They're bringing drugs. They're bringing crime. They're rapists." He was heavily criticised for his comments, but when Miss Steinle was killed he tweeted: "What about the undocumented immigrant with a record who killed the beautiful young women [sic] (in front of her father) in San Fran. Get smart!" Democratic frontrunner Hillary Clinton called Mr Trump's comment's "disappointing" but appeared to signal a change in her view on sanctuary cities, which she's previously supported. "Here's a case where we've deported, we've deported, we've deported. He ends back up in our country and I think the city made a mistake," she said in an interview with CNN on Monday. "I have absolutely no support for a city that ignores the strong evidence that should be acted on," she added.
A:
The killing of an American woman last week by an undocumented Mexican man has reignited the debate over how "sanctuary cities" in the US deal with illegal immigrants. How do they work?