The Sunnah method of slaughter is to drain all of the impure blood from the body of the animal by cutting all of the vessels of the throat including the carotid artery, trachea, esophagus, and the jugular veins. The prophet (saw) said, “Eat from those animals whose blood was drained and upon whom the name of Allâh was recited. The blood can only be completely drained from the body if the vessels of the throat are cut.
In light of this narration, the great Imams of Fiqh have stipulated that a combination of a certain number of these four vessels must be cut in order for the animal to be lawful. For example, the preferred view according to the Hanafi school of thought is that any three of the four vessels be cut. Imâm Shâfi’î requires that the esophagus and the windpipe of the animal be cut. Thus, the slaughter will be valid when these two are cut, even if the two jugular veins are not cut. Similarly, there are also various views narrated from Imâm Ahmad. In one narration, his view is the same as Imâm Shâfi’î. According to another narration, it is necessary to cut the two jugular veins along with the esophagus and the windpipe. In other words, it seems that he has required that all four vessels be cut.  There are also numerous benefits to severing all the vessels of the throat including increased shelf life, absence of bacteria, and complete drainage of flowing blood.
The modern day slaughter method in North America does not ensure that all the vessels of the throat are cut and that the blood is completely drained. This applies in particular to the contemporary method of slaughtering cattle which is known as the ‘European Cut’ or the vertical cut. As the name suggests, the slaughterer cuts the throat of the animal vertically starting from the heart and ending at the throat. This slaughter process does not ensure that the impure blood completely flows out of the animal and up to 18 pounds of impure blood remains in the cow after this slaughter process. Slaughterhouses employ this slaughter method to increase the weight of the animal, better preserve the hide of the animal, and for its convenient nature.
The ‘vertical cut’ is a slaughter method which is contrary to the Sunnah method and does not ensure that the minimum number of vessels of the throat is severed. After consulting with many halal authorities and experts, one arrives at the conclusion that this slaughter process is unacceptable and renders the slaughtered animal as unlawful.
The scholars are unanimous on the fact that the meat of an animal which can be subdued is unlawful to consume if it is killed without cutting the vessels.
Another related issue is with regards to severing the esophagus during the slaughter. Many beef and lamb slaughterhouses in America purposely do not sever the esophagus of the animal for food safety issues. The meat of the animal can potentially become contaminated if food is released from the esophagus during the slaughter process and the company can suffer a loss in the form of less meat production. Therefore, many slaughterhouses either employ the vertical method or clip the esophagus in the middle of the slaughter to ensure that the esophagus is not cut. This process is problematic for Muslims and is sufficient to render the animal unlawful for followers of the Shafi school of thought.
Likewise, there are some slaughterhouses in America which employ a ‘modified’ horizontal cut which combines two cuts; one vertical and one horizontal. One slaughterer first cuts the skin vertically with a sharp knife. A second slaughterer then severs the jugular vein and carotid artery with two horizontal motions at the lower area of the throat, thus nicking the trachea in the process. Again, the common theme is that the esophagus is purposely not cut to avoid food safety issues. To some extent, this slaughter process is slightly better than a pure vertical cut since at least some vessels of the throat are partially severed. However, the minimum number of vessels of the throat which are required by the various schools of thought are not severed in this process. The major portion of three vessels is not cut, rendering the animal unlawful according to the Hanafi School of thought. The esophagus is not cut for the Shafi School of thought. In a similar fashion, the major portion of the trachea is not cut for the Maliki school of thought and the cutting procedure takes place in two separate actions, which violates the condition of valid slaughter of uninterrupted slaughter. The Halal Advocates personally have observed this slaughter process and have arrived to this conclusion after extensive research.
The pure vertical cut, modified vertical cut, and other similar slaughter methods go against the Sunnah method of slaughter and are doubtful methods of slaughter which do not completely fulfill the halal requirements. The best method of slaughter is the Sunnah method which consists of a horizontal cut on the throat of the animal and severing all four vessels of the throat in order to remove all the impure blood from the animal. This is the only method which ensures that the meat slaughtered is lawful for Muslims of all schools of thought to consume and the method which removes all doubts. On this basis, the Halal Advocates of America have stipulated in their HFSAA halal standards that the slaughterer should employ a horizontal cut on the throat of the animal and sever all four vessels of the throat. The Halal Advocates will do their best to work with the industry and slaughterhouses to promote this universal halal standard and educate the Muslim public on the benefits of this Sunnah method of slaughter.