Players with a colortag that is labeled in red above can be legally agressed in empire space (no CONCORD intervention in high sec) but:
Bei <-5– – can legally aggress attackes, which triggers a Limited Engagement Timer; wt, mil and can always legally aggress you.
This is currently also always the case for crp, if friendly fire is legal within your player corporation.
Players having a kr Kill Right on them that you can activate, only turn to legal targets, once you (or someone else) activated it.. Such targets will get a Suspect Timer, aggression follows the rules stated above.