Voter fraud is real — and it is an urgent problem, for which only voter ID is the answer.

The proof arrived in a courtroom in Orange County on Monday, as Brenda Lee Brown Armstrong, 64, pleaded guilty to a felony charge of paying another person to register to vote.

Armstrong allegedly went to Skid Row and paid the most desperate homeless people in the city to register to vote, then obtained their signatures on ballot petitions. She also allegedly used the names and addresses of real voters when signing them up.

She said that she was being paid by higher-ups. We don’t yet know who they are, and how high up the scheme went. We also don’t know how broad the problem is.

But we know it exists.

Thanks in part to the work of citizen journalists, who have caught people in the act, we know how easy it is to pay people to register, or to register dozens of people to uninhabitable locations, like parking lots.

And thanks to Bill Essayli, the top federal prosecutor in the Central District of California, there will be consequences in this case. Perhaps the first of many.

We have been told for years that voter fraud is just a figment of the Republican imagination. Or that the penalty for illegal voting is enough of a deterrent. Or that the authorities catch most of the cases that arise. Or that voter fraud is so rare as to be unimportant.

But all of these are just excuses. The fact is that our current system makes it easy to commit voter fraud — as easy as a trip to Skid Row with a few dollars in your pocket and a clipboard in your hand.

This is part of the reason public confidence in democracy has been falling. The fact is that we cannot say with any degree of certainty that everyone who is voting is doing so properly, and that every vote is being counted accurately.

The only answer is voter ID — the ordinary practice, common in 36 states and most democracies around the world, of proving that you are who you say you are when you register and show up to vote.

It’s not “racist.” It’s just common sense.

Voter ID is favored by the vast majority of voters, even in California — that is, until you tell them that it is a Republican priority. Then people fall back into their party loyalties.

But look past party labels. There is a real chance to pass voter ID this year, one we dare not miss.