Those challenging the ban say it is an infringement of the First Amendment right to free speech. The Justices aren't expected to rule on the constitutionality of the ban but rather if it can be challenged before it is actually enforced.
The ban was started when Rep. Steven Driehaus, D-Ohio, complained that the Susan B. Anthony List, a pro-life group, planned attack ads saying that since Driehaus supported the Affordable Care Act, he therefore supported federally-funded abortions.
Driehaus asked Ohio Elections Commission to block the ads saying they were false and citing the ban. The billboard owner decided not to run the ad for fear of legal action, but Driehaus lost the election anyway and withdrew the complaint before a decision was made.
The Susan B. Anthony List then challenged the law, arguing the ban is unconstitutional.
Critics across the political spectrum seem to agree it would be difficult to define campaign lies and could be a costly venture to monitor.