From The New Yorker, on the then-pending nomination of Harriet Miers to the Supreme Court: "Since inferences are all there will be to go on, every shard will be examined."
From a 2005 editorial in The New York Times: "Since this page endorsed Michael Bloomberg's re-election as mayor, we're obviously glad that New York City voters agreed." From a 2006 editorial in the Times: "Since the Republican majority has decided to allow President Bush to usurp Congress's role..."
Has the point been sufficiently belabored? If so, we conclude with a ban on its first cousin: "The reason is because ..." Three Harvard professors combined to commit this felony in a piece in The Washington Post two years ago: "The real reason Summers'comments offended is because they were made in the context of a history of discrimination ..." Aaarrgh!
And the point is? Writers should never use "since" when their meaning is clearly "because." Even if their names are Souter and Scalia!