Calling Donald Trump's lies "lies" isn't partisan. It's the truth.
Even after President Barack Obama released his longform birth certificate in 2011, Donald Trump repeatedly questioned its authenticity and insinuated there was a conspiracy (including murder!) to keep the truth of President Obama’s foreign birth from the public. Then in September 2016, Trump finally acknowledged that he did in fact believe President Obama was born in the US — and said that he’d dropped the issue after the longform birth certificate came out, even going so far as to falsely blame his opponent, Hillary Clinton, for starting the whole thing.
Trump did something — for years — and then denied he’d done it. Is it fair to call him a liar? Common sense says this is a pretty open-and-shut question. But New York Times public editor Liz Spayd — the paper’s independent ombudsperson — is really, really resistant to the idea that it’s ever okay to say, in so many words, that a politician “lied.” Ultimately, she’s okay with it in the case of Trump’s post-birtherist denials — because it was a particularly sustained and particularly racist kind of lie. But she protests that journalists shouldn’t use the word “lie” just because it’s “factually accurate” that a lie has taken place: "That said, I think The Times should use this term rarely. Its power in political warfare has so freighted the word that its mere appearance on news pages, however factually accurate, feels partisan. It feels, as Ryan said, as if you’re playing the referee in frivolous political disputes."
Calling Donald Trump's lies "lies" isn't partisan. It's the truth. When to Call a Lie a Lie (New York Times)