I've been looking into Halal suppliers and Halal food for as long as I can remember.
One top scholar, Yusuf al-Qaradawi is put on the list of many Halal certifiers so I looked onto his teachings to get a better understanding because some of our own Ulama have quoted him in Q&A's in Halal/Haram Food and you get the idea that if such a name is attached to the label, then it must be fine for us to follow in the Hanafi school.
Here are some of his views:
A Rule: What We Do Not See, Should Not Be Probed Into
It is not required of the Muslim to inquire about what he has not witnessed, i.e., How was the animal killed? Did the manner of slaughter meet the Islamic conditions? Was the name of Allah mentioned while slaughtering or not? If the animal was slaughtered by a Muslim, even if he is ignorant or sinful, or by someone from among the People of the Book, eating it is halal for us.
We have already narrated a hadith in which it was said to the Prophet (peace be on him): “People bring us meat and we do not know whether they have mentioned the name of Allah over it or not. Shall we eat it or not?” and the Prophet (peace be on him) replied, “Mention the name of Allah (over it) and eat.”
Concerning the application of this hadith, scholars say: This is proof that the actions and practices of people are ordinarily considered to be correct and appropriate, while deviation or error must be proved.
And Allah knows best.
Some scholars are of the opinion that although the name of Allah must be mentioned, it is not necessary to mention it at the time of slaughtering the animal; one can mention it at the time of eating, since in that case it cannot be held that it was eaten without mentioning the name of Allah over it. In the Sahih of al-Bukhari we find a hadith narrated by ‘Aisha, who said, Some people who had recently become Muslims said to the Prophet (peace be on him), ‘People bring us meat and we do not know whether they have mentioned the name of Allah over it or not. Shall we eat of it or not?’ The Prophet (peace be on him) replied, ‘Mention the name of Allah (over it) and eat.”
The late scholars Syed Abul A'la Maududi and Al Phahim Jobe both argue that the meat must be slaughtered in accordance with Islamic guidelines.
Scholar Yusuf Al-Qaradawi argues that the meat of the Jews and Christians (called the ‘People of the Book') is acceptable for Muslims to eat.
(The Lawful and The Prohibited in Islam by Yusuf Al-Qaradawi, page 60)
“...we know that imported meats, such as chicken and canned beef, originating with the People of the Book are halal for us, even though the animal may have been killed by means of electric shock or the like. As long as they consider it lawful in their religion, it is halal for us. This is the application of the above verse from Surah al-Maidah.” (Sheikh Qaradawi is referring to Quran 5:5)
Why we can't eat the meat of The People of The Book
Many more investigtions on Halal Food. http://www.muftisays.com/forums/82-the-food-section/