The major requirements of halal slaughter are:
- It must be done by Zabiha 5:3
- It must be done by a believing Muslim, Jew or Christian 5:5
- Allah's name must be pronounced at the slaughter 6:121
- The animal must be alive before the slaughter, must die because of the Zabiha (and not because of the electric-shock etc.) and must be of a permitted species. 5:3
In a non-muslim country, the meat in front of you will be halal when you've personally verified all of the above or have reliable testimony (e.g of a halal or kosher certification authority) that they've verified the enforcement of the above.
On the contrary: In a muslim country, the meat in front of you will be halal by default, unless you've personally verified that it didn't meet one of the criterion or have a reliable testimony of that.
In general, you won't get halal meat in non-muslim countries unless its specially prepared for the purpose. Contemporary Christians are not particular about pronouncing Allah's name. Secular organisations won't discriminate if the slaughterer is atheist, hindu, buddhist, magi, pagan etc.