Ok let me straghten this up...
You can always be podded the question is what happens to the other guy...
Hisec
Player A has GCC, Player B --- can shoot his ship but not his pod without gaining GCC himself
Player A is at war with player B --- both pilots can pod each without consequence
Player A has agression with player B --- Player B can shoot player A, player A can only shoot back once player B opens fire. Neither player can pod each other without GCC occuring
(ie player A stole from player B)
Player A has security status lower than -5 --- Player B can pod player A in any system without consequence
Lowsec
Player A has GCC --- Player B can shoot and pod player A without consequence
Player A is at war with player B --- Both parties can shoot and pod without penalty
Player A has agression with player B --- Same as hisec
Player A has security status lower than -5 --- Same as hisec
Null / Wormhole
No consequence for shooting pods
Gaining GCC in hisec will spawn concord if you are flying a ship. Sentry guns at stations and gates will fire upon your ship. Neither gate or concord will fire on your pod
Gaining GCC in lowsec means sentry guns at stations and gates will fire upon your ship. Neither gate or sentry guns will fire on your pod
Consequences for breaking the above rules
You take a security hit for unlawfully agressing and a second one for destroying a ship unless it fires back. You take a large sec hit for destroying a pod. The size of the security drop depends on your current sec status, your opponents sec status and the sec status of the system you are in.
Eg podding a 5.0 character in 1.0 space gives a bigger hit than a -4.9 character in 0.1 space.
Disclaimer
This is info from memory and may be partially inaccurate