I am doing things a bit differently today. I often write to you after an important voting decision with an analysis of the outcome. Today, I can confidently write to you in advance of an expected victory for voting rights in federal court in Massachusetts.

At some point before Tuesday, I expect Massachusetts Federal Judge Indira Talwani to rule that the Trump administration's plan to weaponize the U.S. Postal Service against mail-in voting is unlawful and unconstitutional. It will be the fourth or fifth time she has done so — depending on how precisely you count.

Regardless of the number of opinions, the judge is nearly certain to decide once again that the Postal Service's rule requiring states to turn over voter lists and abide by strict new envelope designs infringes on state power to set election rules.

The current restraining order blocking the USPS from implementing its new anti-voting rule will be replaced with a more durable injunction. This will allow states, for now, to finalize their mail-in ballot materials and make plans to send them out to voters.

But that order will not be the last word on this matter.

At every stage, the Department of Justice has remained committed to defending Trump's unconstitutional power grab. The DOJ has already appealed two prior defeats at the hands of this same judge.

After the First Circuit upheld her earlier injunction, the Supreme Court vacated it in late August, saying that the USPS had not yet acted and thus the legal claims were not ripe.

Now, with a final USPS rule in place, that is no longer an issue. The DOJ cannot avoid the merits of the case. It must defend Trump's executive order and the USPS's rule implementing it. That is a nearly impossible task.

Its arguments are vague and disingenuous. The DOJ has suggested that the USPS's actions are ordinary and routine. Nothing could be further from the truth.

Heading into November, this is one of our most important battles yet, with the future of free and fair elections hanging in the balance. However, I am worried that this is being viewed by the public and legacy media as just another fight over voting rights between the Trump administration and pro-democracy advocates. It is not...