There are a few articles floating around the internet today, which I'm sure some DT dipshit will come post in this thread, about how the conservatives took the private right of action from the liberal playbook and liberals are being hypocrites by complaining about it in this context. I'm just going to go ahead and pre-emptively explain why that's bullshit. Private rights of action in laws that liberals have historically supported are created (1) to give people a right to protect their own rights (e.g. to sue for unlawful discrimination), or (2) to enforce environmental laws. They're created to ensure that the purpose of an applicable law isn't defeated by the refusal to enforce it by state actors. However, SB8 specifically created a private right of action for the clear purpose of avoiding judicial review. This is so completely different that it is utterly dishonest to pretend that it is similar to how private rights of action have been used in the past.
However, there is an historical law that this law does appear to borrow from. It's not a civil rights law, or an antidiscrimination law, or an environmental law though. It's the Fugitive Slave Act of 1850. The Fugitive Slave Act allowed states to appoint anyone they wanted as bounty hunters to hunt down and capture escaped slaves. It allowed someone who simply claimed to own an escaped slave to swear that a black person was their slave and required that the state accept such a sworn statement as conclusive and forbid the testimony of an alleged escaped slave to be admitted as evidence to the contrary. And it subjected anyone who aided, abetted, or assisted an escaped slave to fines, imprisonment, and civil liability of $1,000 per alleged-escaped slave that they aided, to be paid to the alleged-slaveowner.
It is hard not to conclude that the Texas legislature used the Fugitive Slave Act as a model for SB8.