Can states legitimately enact immigration law or policy that is contrary to federal immigration law?
<p>Federal Immigration and Nationality Act Section 8 USC 1324(a)(1)(A)(iv)(b)(iii) says</p>

<blockquote>
  <p>Any person who encourages or induces an alien to reside in the United States, knowing or in reckless disregard of the fact that such residence is in violation of law, shall be punished as provided - for each alien in respect to whom such a violation occurs fined under title 18, imprisoned not more than 5 years, or both.</p>
</blockquote>

<p>That said, does it follow that it would be a violation of Federal law for a government official to declare a state/city to be a "sanctuary state/city" for the specific purpose of harboring and protecting unauthorised immigrants from lawful deportation?</p>

<p>No, it does not follow. </p>

<p>Mostly, because that's not what is actually happening with sanctuary cities. First, there is no actual definition of a sanctuary city, neither in the law or, more specifically, in immigration policy. </p>

<p><a href="https://www.washingtonpost.com/news/fact-checker/wp/2017/04/28/the-white-houses-claim-that-sanctuary-cities-are-violating-the-law/?utm_term=.29d870edc373" rel="nofollow noreferrer">Here's what happens in sanctuary cities</a>. Section 1373(a) of Title 8 of US Code states that local and state governments are prohibited from enacting laws or policies limiting the exchange of info re: citizenship w/Department of Homeland Security. So if you work for the local Department of Human Services, and someone shows up to sign up for public benefits and you find out they are undocumented immigrants, if you wanted to report that person to ICE, no government could forbid you from doing so. Conversely, the federal government can't force you <em>to</em> report that undocumented immigrant. </p>

<p>Likewise, the detainers that ICE issues, which are requests to the local government to inform them when a given undocumented immigrant is to be released, are not mandatory. If that action is taken, the jail can hold the undocumented immigrant up to 48 hours for ICE to act. If ICE doesn't act, the person must be let go. </p>

<p>A report by the DOJ's inspector general looked at a random sampling of cities that receive federal funding and found that each of them had certain policies in place that limited cooperation with ICE and ICE's detainers. However, the same inspector general found that Section 1373 is not applicable to detainers. In sum, the IG determined that, although there were no explicit policies forbidding state or local employees from cooperating with ICE, non-compliance with detainers in <em>some</em> jurisdictions at the very least were "inconsistent with ... the intent of Section 1373." </p>

<p>Legal arguments abound. One argument is that the administration is interpreting Section 1373 too broadly in order to include both types of sanctuary cities. Another is that Section 1373 violates the anti-comandeering doctrine of the 10th Amendment. </p>

<p>I guess the real answer is, "stay tuned," but for now, no it does not follow that it is a violation of federal law for a government official to declare a state/city to be a "sanctuary city." </p>

united-states criminal-law immigration jurisdiction