Why is illegal immigration a controversial issue?

It's a controversial topic because of the different opinions have. Some people like to follow laws like illegal immigration but then completely disregard other laws while other people blame illegal immigration on a fail by the said country(probably the U.S.). The different opinions of people make it a controversial topic because anything can be a controversial topic if it's made into a topic that has conflicting opinions- that which is every topic under the sun, basically.

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