Legal Question in Civil Rights Law in California

You are always governed by the laws of whatever jurisdiction you're in. Your California medical card is valid . . . in California. If the particular state you're visiting has a similar law and you meet all the criteria, then you *might* be okay. I only say "might" because you would have to look at the specific language in the other state's law to see what requirements, limits, limitations, etc. they place on their compassionate use act (if they even have such a law).

There is still the Federal issue, too. Even with the latest proclamation that medical marijuana dispensaries that are acting in compliance with state law shouldn't be raided by the Feds, the same can't necessarily be said about traveling with marijuana.

There's no way I'm even going to touch the prospect of traveling, whether within the country or internationally, with marijuana. Your California recommendation potentially means very little to another state and it means absolutely nothing in a foreign country.

Bottom line: A California medical marijuana card covers California. From there, it's dicey whether or not it has any significance at all.

None. You are in violation of federal law, and subject to arrest now. California and some cities delusionally ignore that when giving you your card and telling you 'everything will be all right'. The feds could take action any time, but have chosen for the time being to remain inactive.