What do black arrows mean in Democracy 3?

//ads -- adsterra.com -- native banner
?>
I'm trying to start playing Democracy 3, but I'm having a little difficulty with the UI. I understand that a green arrow means a positive relationship and a red arrow means a negative relationship, but what does a black arrow mean?
For example, in this screenshot:
Narcotics are currently illegal. What does it mean that Narcotics has black arrows pointed towards Legal Drug Consumption, and Legal Drug Consumption has black arrows pointing towards Health, Productivity, and Alcohol Consumption?
Pictures about "What do black arrows mean in Democracy 3?"



How To Improve Your Economy In Democracy 3
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Ketut Subiyanto, Brett Sayles, Mathias Reding, Jakayla Toney