Pull all border agents from the southern border of California, and place border protection on California's borders with Arizona, Nevada, and Oregon.
Of course it would be preposterous to do such an undertaking (or maybe not).
However, how preposterous is it for California to expect the federal government to control its borders and then not only ignore our immigration laws, but to also interfere by aiding and abetting illegal aliens?
I don't think a lawsuit is worth the time. Congress needs to take punitive action against the People's Republic of Kalifornia (PRK).
The PRK has discussed seceding from the United States. As tempting as it may sound, it would totally backfire on the once-Golden State. I did a podcast last year explaining why.
Illegal aliens cost California taxpayers more than $25 billion a year, while only receiving an estimated $5 billion in tax revenue from illegals. And their state legislators wonder where all the money goes...