In the Oscar Grant murder trial, jury selection is underway and opening statements are set to begin later this week. But much of the case is already being shaped by pre-trial motions made by ex-BART cop Johannes Mehserle’s defense.

California Beat reports that Judge Robert Perry will rule soon on two motions filed last week by Mehserle’s attorney Michael Rains, who is trying to keep jurors from hearing about an exchange between another BART cop and Oscar Grant minutes before Mehserle shot 22-year-old Grant in the back on the train platform on New Year’s Day 2009. According to court documents, BART cop Tony Pirone and Grant traded racial slurs; Grant called Pirone a racial profanity and Pirone repeated the phrase back to Grant several times.

Rains wrote in his motion that people would not be able to separate Pirone’s conduct from Mehserle’s:

Although Mehserle is white and Grant is black, this case is not about race. Mehserlse has not been charged with a hate crime. There is no evidence he expressed any racist sentiments or acted out of some racist purpose…The danger, of course, is that the jurors will take the inappropriate conduct of one man and generalize it to BART police in general, and to the defendant specifically.