Well the arguments there vary from illegal immigration shouldn't be a crime to the punishment doesn't fit. That's not the same thing as saying don't punish criminals. It's saying that they either shouldn't be criminals or that they're being too harshly punished.

In addition, many undocumented people were brought here as young children or babies. It isn't fair to punish then for the crimes of their parents, especially not when this is the only country and life they've ever known, some may not even know that they were undocumented.

If you want to argue this, I'm not someone who thinks we should have 100% open borders. I just think undocumented people brought over as children shouldn't be considered to have committed a crime and be removed from the country, we need to massively reform the process of immigration to allow for a more fair and open system, there needs to be more humane treatment of undocumented people that are detained, and a border wall is a stupid waste of money that needlessly antagonizes a neighboring country given that the large majority of people don't come here by crossing the border.

An example of a reform would be the fact that most crops in this country are picked by undocumented people. It's not like a lot of citizens want to do that job, and it's not like a lot of farmers want to pay US wages to have it done. Let's just admit both of those things and create a work visa that would allow for people to come here for part of the year and work on farms legally for a lower minimum wage level while requiring the farmers and workers to pay employment taxes that could be used to fund healthcare and housing needs for them while they're in the country. We could also look into creating a special permanent resident or citizenship process for those with student visas that is better than the current system we have for them. Given that many undocumented people were students that overstayed their visa, that gets them paying taxes and not being afraid of being deported. Plus why not encourage college graduates to live and work here permanently. Our society isn't so hurting for spaces that we don't have room to grow larger.