What did Donald Trump do today?

He plugged his son's book again, this time with a new kind of lie.

Trump once again used his office to promote a family member's business today, plugging his son Donald Jr.'s book on Twitter for the second time in as many weeks. Trump claimed that the book was at the top of the New York Times bestseller list before demanding that his supporters "keep it there."

Trump is actually telling the truth, as far as it goes: Trump Jr.'s book is, in fact, at the top of the list this week. But for decades, the NYT list has put a dagger (†) symbol next to books where the sales figures have been artificially inflated by bulk purchases. This is rare, and usually happens with political books, where political organizations can use large purchases to funnel money to an influential author while saving him the embarrassment of low sales figures. 

Trump Jr.'s book received the dagger. No other book currently on the list did—and this week's list includes a book about "gutsy women" by Hillary Clinton and Chelsea Clinton, a book about Russian oil barons by progressive MSNBC host Rachel Maddow, and a book about serial sexual predators and how the media protects them (in which Trump Sr. is discussed) by journalist Ronan Farrow.

The Republican National Committee, which is effectively an arm of Donald Trump Sr.'s 2020 presidential campaign, has admitted to giving away freebie copies of Trump Jr.'s book to donors. It has refused to say how many copies of Trump Jr.'s book it has purchased.  

Any other government employee promoting a family member's business this way would be subject to prosecution.

So what?

• It's always wrong to use your public office for private gain, even if you can get away with it.