This is what open borders get's you.

[Aimless]

I hadn't heard about sanctuary cities before, I wonder what the rationale behind those policies may be.

[LittleFuzzy]

I hadn't heard about sanctuary cities before, I wonder what the rationale behind those policies may be.

They don't like federal policy so by local ordinance they enact legislation requiring non-cooperation to whatever extent they are able. The various federal law-enforcement agencies are generally rather specialized and have limited scope in the use of their powers, they rely on interagency cooperation both with other federal agencies and with state and local law-enforcement. They also have much more limited manpower as one would expect from that degree of specialization. Which means if local law enforcement doesn't bring them in, their capabilities become far more constrained. It's basically the same problem as seen with militias and militia-cooperating local authorities on the border only in reverse.

[Hazir]

Which open borders I wonder.

[Lewkowski]

I hadn't heard about sanctuary cities before, I wonder what the rationale behind those policies may be.

It depends on the individual city but a lot of liberals think illegal aliens have every right to be US citizens because we 'stole' the land from Mexico. For others it isn't about the principal it is just about pandering to actual citizens who view illegal immigrants with sympathy.