All their recent cases in my memory are left-leaning at least, which, while they do represent many good goals in my opinion, is understandably a political slant.
From: https://www.aclu.org/defending-our-rights/court-battles
Some recent cases;
* The ACLU filed a motion in Michigan state court challenging the constitutionality of a subpoena issued to the website PubPeer demanding that it turn over the identities of anonymous commenters
* The ACLU has filed a lawsuit challenging the constitutionality of the NSA’s mass interception and searching of Americans’ international communications.
* Whether a cause of action is available under the Constitution for violations of prisoners’ due process and equal protection rights when the prisoners were abused in immigration custody and when the government.
* Whether North Carolina can prohibit individuals who are registered sex offenders from “accessing” any social media websites.
* In a Freedom of Information Act request filed on January 13, 2010, the ACLU asked the government to disclose the legal and factual basis for its use of predator drones to conduct "targeted killings" overseas.
They do a lot of good work.
However I'm not just talking about that, I'm also talking about them defending civil rights for everyone, not just those on the left. They used to be very good about this, standing up for protesters on both sides for example, but now I'm not so sure.
https://www.washingtonpost.com/news/the-fix/wp/2015/06/19/a-...
That's not how most "just a left-leaning political organization"s behave.