LaMonica McIver

The legal face-off between the Justice Department and Representative LaMonica McIver of New Jersey is set to continue in federal court this week. And the stakes are high.

Ms. McIver was charged with assaulting federal immigration agents a year ago, and on Wednesday her case will be argued before a panel of appellate judges.

To Justice Department prosecutors, the case will offer an opportunity to limit the bounds of congressional immunity.

To Ms. McIver the prosecution holds personal and political peril: up to 17 years in prison and an estimated $1 million in legal fees, just as she is running for a second term.

And to a bipartisan group of former Congress members, the charges represent an existential showdown between the executive and legislative branches.

“If the Department of Justice is allowed to proceed with this prosecution, it would create a perverse incentive for Executive Branch officials to act in a more chaotic and unsafe fashion, and create new, unprecedented tools to block legitimate legislative oversight,” wrote lawyers for the 20 former members — 17 Republicans and three Democrats — in support of Ms. McIver’s effort to have the assault charges dismissed before trial.

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.