Freedom to Read Foundation General Counsel Theresa Chmara has written an article for American Libraries magazine discussing recent court decisions in Washington and Missouri affecting Internet filtering in libraries:

Why Recent Court Decisions Don’t Change the Rules on Filtering

Several libraries have been sued recently on the grounds that their internet filtering programs are unconstitutional, raising questions in the library community about whether the rules have changed about blocking software.

The short answer is no.

In discussing a federal judge's recent decision in the case Bradburn v. North Central Regional Library, Chmara explained that:

The fact that the district court in one case upheld an internet filtering system does not mean that other libraries can be assured of a similar result.

In another recent case involving a school library, the US District Court for the Eastern District of Missouri reached a different conclusion. The court held on February 15 that the school district in Camdenton, Missouri, had unconstitutionally blocked websites that support or advocate on behalf of lesbian, gay, bisexual, and transgender (LGBT) people while permitting students access to websites that condemn homosexuality or oppose legal protections for LGBT people.

In that case, the district had to pay significant legal expenses.  Chmara concludes by noting:

If libraries use filters that block constitutionally protected material deemed harmful to minors and do not allow adults to disable filters, or fail to provide an effective unblocking system, those libraries may open the door to years of litigation and significant legal expenses.