( CNN ) -- Renisha McBride 's toxicology report is out and now we know the 19-year-old had a blood-alcohol level that was more than twice the legal limit for driving . This would explain why , according to her family , she was involved in a single-car accident . However , it does not explain why Theodore Wafer shot her in the face . McBride 's family says she was seeking help after the crash and knocked on the door of Wafer 's house in Dearborn , Michigan , a suburb of Detroit . The 54-year-old Wafer , who is white , told investigators he feared McBride , who is black , was trying to break in . There are too many unanswered questions to know exactly what happened that night . But we do know this : If a black man told police officers `` self-defense '' was the reason why he shot an unarmed white teenage girl in the face with his shotgun , it would not have taken protests , national media attention and nearly two weeks for authorities to reject that excuse . And this is why McBride 's death -- ruled a homicide after protests and national media attention -- draws comparisons to that of Trayvon Martin , the Florida teen shot and killed by George Zimmerman , who is of white and Latino heritage , last year . Not that the events leading up to their shootings are identical . They are not . But statistics show the benefit of doubt granted to those who have spilled black blood is not extended as graciously when roles are reversed . In other words , if someone told you a black man stalked , confronted and eventually murdered an unarmed white teenage boy , it 's doubtful `` self-defense '' would get him off the hook . And it should n't , because that sounds ridiculous . But when the victim is black , the narrative that has historically characterized blacks as a menace -- the narrative that gets supported by out-of-context crime statistics , pop culture imagery and media coverage -- assigns culpability and thus plausibility . On Friday , Wafer was finally charged with second-degree murder , manslaughter and possession of a firearm in the commission of a felony . We 're finally on the road to finding out the truth , and perhaps even achieving justice for McBride . But will another high-profile , racially charged murder trial get us any closer to debunking the strain of thinking that places `` fear for one 's life '' and an unarmed , dead black person in the same scenario far too often ? This is the same idea that says it 's completely reasonable for the NYPD to continue to `` stop and frisk '' â€ ” a practice that disproportionately targets black people , despite its resulting in confiscation of a gun one-tenth of one percent of the time . It 's the idea that says two police officers , who fired 15 shots at an unarmed , 60-year-old black man in his own driveway , are the victims . It 's the idea that says there 's no need to quickly make an arrest -- even though McBride 's unarmed body is lying in a pool of blood and the nearby weapon is still warm -- because the killer may have `` acted as a reasonable person would who was in fear for his life , '' as Cheryl Carpenter , the lawyer of the alleged shooter , claims . Between 2005 and 2010 , an Urban Institute study , using FBI data , found that white-on-black shootings were found to be justified 11.5 % of the time in states that do n't have stand-your-ground laws and 17 % of the time in those that do -- the highest among all combinations . Black-on-white homicides were ruled to be justified 1 % of the time in stand-your-ground states and even less frequently in states without the law . Now , obviously statistics do n't reveal the circumstances surrounding each shooting , but they do reinforce the narrative that black people are inherently more dangerous . Thus Pasadena police were found `` justified '' in killing a black , unarmed 19-year-old college student who was falsely accused of robbery . Los Angeles police who shot and killed an unarmed black , autistic 27-year-old did so `` in defense of their lives '' according to their attorneys . It 's the same fear that led four police officers to fire 41 shots at an unarmed black man on the stoop of his New York apartment in 1999 , hitting him 19 times . It 's the same fear that led an officer to shoot and kill an unarmed 24-year-old black man who , like McBride , was reportedly in a single car accident and went out looking for help earlier this year . You can tell yourself all these stories are just tragic one-offs if it makes you feel better . Parents of black children do n't have the luxury . Sure , there are plenty of examples of blacks committing crimes but how does that justify pre-emptive strikes ? How does that make substituting `` open season '' with `` self-defense '' , OK ? I remember something former NFL player Dhani Jones once told me : `` A lot of upper-middle-class black people hear reports about a black athlete and assume he 's guilty . ... If he 's innocent , they 'll see it more as a special case than the norm . '' This attitude extends to society as a whole . Assuming black people are inherently up to no good is not just something some white people are guilty of . There are blacks who are leery of blacks as well . That is the power of the narrative . That is the subtlety of institutionalized racism . It does n't wear a hood or burn crosses in a yard . Rather it 's the subconscious element of our culture that looks at a black corpse and quietly puts it , instead of the perpetrator , on trial . The opinions expressed in this commentary are solely those of LZ Granderson .
Renisha McBride , black teen , was shot dead after knocking on a white homeowner 's door . Family says she needed help ; homeowner says he feared she was breaking in . LZ : If a black man said he shot unarmed white girl in the face in `` self defense '' he would be in jail . LZ : Our culture `` looks at a black corpse and puts it , instead of the perpetrator , on trial ''