Leicester City face being charged by Uefa after FC Copenhagen fans let off flares at the King Power Stadium before Tuesday's Champions League match.
The Danish champions also face sanctions from European football's governing body over the flares.
But Uefa holds host clubs responsible for security inside and around the stadium before, during and after games.
A home club in a Uefa competition can be sanctioned "unless they can prove that they have not been negligent".
The regulations come under article 16 of the European governing body's competition rules, which cover the Champions League.
In October 2014, Arsenal were charged initially over flares thrown on to the pitch by Galatasaray fans at Emirates Stadium.