Can publishing a link infringe a copyright?
In the EU, the issue is settled -- linking to copyrighted content can infringe a copyright.
According to the Court of Justice of the European Union, under Directive 2001/29/EC of the European Parliament (see the EU Copyright harmonization directive), the key issue is whether the link constitutes a "communication to the public" (See Svensson and Others v. Retriever Sverige AB, Case C-466/12, Feb 13, 2014; GS Media BV v. Sanoma Media Netherlands BV and Others, Case C-160/15, Sept 8, 2016). To make this determination, you must examine whether the content being linked to was published with the copyright holder's consent (Compare Svensson and Others, Case C-466/12, (finding copyright holder authorized the publication of the linked content) and GS Media BV, Case C-160/15 (finding copyright holder did not authorize the publication of the linked content)) (see also my earlier blog post on Brein v. Ziggo BV an Others, Case C-610/15, June 14, 2017 (finding BitTorrent tracker files constitute a communication to the public and infringe the copyright holder's rights)).
In the US, this issue could be reopened. Playboy recently sued the website BoingBoing for reporting in a blog post on the fact that a third-party had uploaded every Playboy centerfold and providing a link to that publication (see Playboy Entertainment Group, Inc. v. Happy Mutants, LLC, C.D. Ca., November 11, 2017). While it is always possible to sue, the likelihood of winning its copyright infringement argument is not high because of differences in US and EU copyright law. That said, if this lawsuit isn't dismissed or settled, then the court will address this issue.