Yes, probably under 42 USC sec 1983. You will not easily find an attorney, because attorneys need to feed their families and pay their mortgages like anyone else. Unless the case is won they will have invested a great amount of time with no payback.
In general, the complaint would need to allege soemthing that anyone--not just you--would think is completely outrageous, and for which there is documentary proof, not just your word, and finally that there is some damage to you or your kids that can be compensated with money.
And of course their needs to be a constitutional violation by CPS. That would likely be taking some kids away with no hearing before or after the taking. Simply that you think you are capable of taking care of your kids and they do not will not be enough.
Your best bet is to try to get ACLU to take your case. I will place a link.
Licensed in Maryland with offices in Maryland and Oregon. Information here is general, does not create a lawyer-client relationship, and is not a substitute for consulting with an experienced attorney on the specifics of your situation.
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