Too much power in the hands of the state can be a terrible thing. Now is one such time, and Texans must remain vigilant.

Last week, a federal appeals court granted the state permission to begin enforcing its ban on so-called sanctuary cities. The tools with which the Texas Legislature has given to the state are unnecessary, recklessly broad and ripe for abuse.

The law, known as SB 4, is no ordinary law. It appears to forbid local officials from setting rules for when an officer may demand proof of citizenship when making an arrest or traffic stop. Each individual police officer will now use his or her discretion in demanding papers.

Should police or other city officials choose to establish norms for when such demands are proper and when they might not be, these officials will be subject to penalty.

The law also forbids local officials from enforcing or creating any policies or local ordinances that would "materially" interfere with federal immigration officers' efforts to enforce immigration laws. And the law requires local officials to cooperate with federal officials, including honoring immigration officials' requests for so-called detainers.

Federal agents routinely request such detainers that local officials keep suspects in jail beyond when they are otherwise eligible for release, if agents believe they may be here illegally. Until now, whether to honor such federal requests have been up to the discretion of local officials. We'll point out here, that such local discretion is an important protection of an individual's right not to be detained without due process. In many cases, the feds are asking to hold onto someone even after there is no further grounds under state or local law to detain them. SB 4 requires local officials to presume federal agents have probable cause for holding a person, no matter how flimsy the grounds for the request may be.

The full scope of the law won't be known until it is tested in the real world. How literally, for instance, will courts read the prohibition against "materially" interfering with federal immigration enforcement? How broadly will the state interpret the requirement that local agencies assist federal officers?

What if, for example, the Dallas County sheriff turns down a request for a dozen deputies to accompany a federal agent on a raid because she thought it was too many officers or that the grounds for such a raid were speculative? Could she be fined or removed from office?

Ordinarily, these limits are tested in the courts. That will happen this time, too, but the difference is that this law puts local officials personally at risk if they tested the law by, for example, pushing back against federal requests. That means local officials will have a clear incentive not to stand up for individual rights in these cases.

That's a chilling thought as Texas Gov. Greg Abbott promises that this law will be enforced. Our system of checks and balances goes a long way to ensuring that we remain a nation of laws. So as Texas now enforces this law, it is crucial that all Texans insist that it does so with fairness, restraint, and integrity.

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