That’s some legacy Michael Grimm is leaving New York: an expensive special election for the congressional seat he’s about to resign, and a new opportunity for the Rev. Al Sharpton to inject himself into politics.

As we predicted, Grimm this week bowed to pressure from House GOP leaders and agreed to quit his Staten Island-Brooklyn seat after pleading guilty to federal tax-evasion charges. This, just two months after winning another term even while under indictment, and all the while insisting he would be vindicated.

As a result, New York now has to hold a special election that will cost taxpayers more than $1 million and probably attract few voters. Already it looks to be ugly.

Republicans appear to be coalescing behind Staten Island District Attorney Dan Donovan, who oversaw the Eric Garner case. The grand jury’s decision not to indict a police officer in Garner’s death is likely to be raised against him.

Indeed, Sharpton is already warning that if Donovan becomes a candidate for the seat, it “would energize those of us who have been dealing with the whole protest movement since Day One.” Then again, the Rev. Al has never been one to miss an opportunity to preen for the TV cameras.

But Sharpton’s warning underscores a point we’ve made all along. Given the protests that have followed the grand jury’s decision, New Yorkers need the Garner transcripts and evidence made public — including the medical examiner’s report.

By all means, let Dan Donovan answer questions about how he handled the Garner case. But let’s not leave it to the Rev. Al to decide what the facts are.