Anyone else tired of the perpetually petulant Donald Trump blaming former President Barack Obama for, well, everything?Boo-hoo, the air conditioning makes the White House too cold. Waaa, it’s unlawful for Turkey to buy US fighter jets because it purchased missiles from Russia. Hmmph, Iran is restarting its nuclear programme after I junked the international treaty Obama negotiated that put the whole thing on ice for at least ten years.On Wednesday, hours after some yapper on Fox & Friends said: “This moment right now is on Barack Obama, not Donald Trump,” the 45th President of the United States blamed the 44th.“The missiles fired last night at us and our allies were paid for with the funds made available by the last administration,” Trump mewled. “The very defective [Iran nuclear agreement] expires shortly anyway, and gives Iran a clear and quick path to nuclear breakout.”As The Washington Post noted, “None of those things is true.”By now, I had come to dismiss the “Obama’s to blame” excuse as nothing more than white noise. An excuse used to sully a man whose decency and character command respect and admiration around the world, unlike his successor. But the Fox News discussion about Trump’s Iran mess being laid at Obama’s feet took me back to October 25, 1994, and a lake in Union County, South Carolina.For nine days, the nation believed Susan Smith. As the Charlotte Observer reported in a story marking the 20th anniversary of the infamous event, “Smith said she was stopped at a red light at an intersection behind the Monarch Mill Textile Plant, which is close to Union’s Main Street, when a black male forced her out of the car at gunpoint and drove off with her two small sons in the back.”But then Smith confessed to killing her 14-month-old and three-year-old sons by letting her car roll into the John D. Long Lake with them strapped in their car seats in the back. Why? The man with whom the married-but-separated woman was having an affair broke off the relationship because he didn’t want children. A jury found her guilty of murder and sentenced her to life in prison with the possibility of parole after 30 years. Quite a different ending than another infamous “black guy did it” tale.The Post’s Diane Bernard reminded us last week that on January 4, 1990, Charles Stuart jumped off a bridge in Boston. Why? Police named him as the prime suspect in the murder of his pregnant wife.As Bernard writes, “Charles falsely claimed that a black man jumped into his car one night in October 1989 and shot him and his wife, Carol, after they attended a Lamaze class at Brigham and Women’s Hospital in the city’s Mission Hill neighbourhood. The supposed gunman, described by Stuart as an African-American man in a track suit with a raspy voice, then shot Charles in the side. Carol was taken back to the hospital where she gave birth to a premature son, Christopher, and then died on the operating room table. The injured baby died 17 days later.”Raymond Flynn, then the Boston mayor, ordered a manhunt. According to Bernard, what ensued was “the police force’s widespread use of stop-and-frisk in its search for the alleged murderer”.It was mass targeting and humiliation on an obscene scale. Bernard interviewed Frederick Johnson, a resident of the Roxbury neighbourhood in Boston. Recounting the harrowing scene he painted for her, Bernard wrote: “During those first few days, African-American men were lined up on street corners with their pants pulled down as officers searched their trousers and underwear for drugs, guns or any excuse to arrest them.”Because of the Stuart case, a lot of African-Americans were super sceptical of Susan Smith from the jump. You might say we, as a people, are used to the ease with which others accuse black men of all manner of offences. It is a deep scepticism woven into our DNA by the savagery of slavery and reinforced by the mutilated body of Emmett Till during Jim Crow, not to mention the countless more recent examples. What troubles us even more is the ease with which others are quick to believe the lie.No, blaming a non-existent black guy for murders you actually committed is not at all the same as blaming a real black guy for political problems you actually caused. Still, it’s not hard to see how Trump’s and the Right’s constant harping on Obama for their every personal, moral and professional shortcoming and failure follows a vile tradition.No one should be surprised by this. Trump rose to prominence peddling the racist birther lie that the nation’s first black president wasn’t born in the United States. Trump then got elected by running a campaign that peddled in the kind of racial grievance that puts the blame for one’s own failings on someone else. African-American men have been the scapegoat of choice since the founding of the republic. So, for Trump, blaming Obama two years and 352 days — as of this writing — after he left the White House comes naturally.•Jonathan Capehart is a member of The Washington Post editorial board, writes about politics and social issues, and is host of the Cape Up podcast