The Pesukim in Parshat Emor  introduce us to the prohibition of eating the new grain until the Korban Omer is brought:
ולחם וקלי וכרמל לא תאכלו עד עצם היום הזה עד הביאכם את קרבן אלהיכם חקת עולם לדרתיכם בכל משבתיכם:
The Sefer HaChinuch  explains to us to the underlying message we can derive from the mitzvah is that since grain is the most essential food of substance that Hashem gives us to live and in order to recognize Him we refrain from enjoying it until a Korban is brought before Hashem similar to a Bracha prior to indulging in food. [It should be obvious that this is only a nice idea one can learn from the Torah but certainly not a halachically binding reason.]
There’s a major discussion about the applications of this prohibition especially nowadays and outside Israel. Because this is an issue that has existed for many centuries there’s a plethora written on the topic and hopefully B”H this article will summarize the main points that are relevant for the contemporary issue.
When does the Grain becomes permitted?
- In the times of the Bet HaMikdash the grain was permitted with the bringing of the Korban Omer (which was brought on the 16th of Nissan), however, nowadays that there’s no Korban it’s forbidden until the 17th of Nissan. Outside Israel where we keep two days of Yom Tov, it’s forbidden until the 18th of Nissan. 
What is new grain?
- Grain which took root after the 16th of Nissan is called Chadash and is forbidden to eat until the 17th of Nissan in Israel and until the 18th of Nissan in the Diaspora. 
- There’s a dispute whether we can assume that grain has taken root after 3 days or only after 2 weeks. 
- Only the five species of grain are forbidden which are usually translated as wheat, barley, spelt, oat, and rye. 
Extent of the prohibition
- There’s a dispute whether the pots which were used to cook Chaddash take on a prohibited status from the absorbed taste. 
- There’s a dispute whether Chaddash applies to drinks made from the grain of the new crop. 
Getting benefit from Chaddash
- It’s permissible to get benefit from new grain and one would be allowed to give it to one’s animals. 
- There’s a dispute whether it’s prohibited rabbinically to sell Chaddash as it could bring a person to eat it. 
Grain that grew outside Israel
- According to most authorities this prohibition also applies to grain that grew in the Diaspora. 
- In Israel the grains are grown in the winter and aren’t harvested until Pesach, whereas, in Europe and America, grains are also grown during the spring (many a time after Pesach). 
Grain of non-Jews
- According to most authorities this prohibition also applies to grain that was grown by a non-Jew. 
Defense of the Minhag HaOlam
- There are some who defend the widespread minhag to be lenient about Chadash. One defense is that some say there is a double doubt, perhaps the grain one has was grown last year and even if it grew this year perhaps it took root before the 16th of Nissan, however, many disregard this logic. 
- Another defense is that the minhag relies on the opinions that Chadash is Derabbanan and only applies in the lands near Eretz Yisrael. 
- Another defense is that the minhag relies on the opinions that hold that grain which was grown by non-Jews is exempt from Chadash. 
- Lastly, some defend the minhag with a different double doubt, perhaps the grain one has is grain from last year and perhaps the law of Chadash doesn’t apply to grain that grew in the Diaspora or to grain that was grown by a non-Jew. 
- A Sephardi who isn’t careful on not eating Chadash in the Diaspora shouldn’t be called up for the Aliyah of Levi on the Yom Tov of Sukkot (when we read about the prohibition of Chadash), however if it will cause a fight it’s permissible to give him the Aliyah. 
- Vayikra 23:14
- Sefer HaChinuch (Parshat Emor Mitzvah #403)
- The Mishna in Menachot 68a says that when there was the Bet HaMikdash the korban Omer made it permissible to eat the new grain and those who lived far enough away and didn’t know when the Korban was brought could assume that it was brought prior to midday because the בית דין wouldn’t tarry in bringing the Korban. However, now that there’s no Bet HaMidash the Mishna says that Rabban Yochanan established that it was forbidden the entire day of the 16th. The Gemara Sukkah 41a-b explains that it wasn’t that Rabban Yochanan enacted a תקנה but rather he made a drasha (exposition) in reading the pesukim and concluded that it was forbidden biblically to eat the new grain until the 17th.
- There’s a dispute in the Gemara Menachot 68b about whether in the Diaspora the prohibition is extended a day just like we extend Yom Tov to a second day. The Rishonim (Rif Menachot 28a, Rosh Menachot 42, and Rambam Maachalot Asurot 10:2) hold like the stringent opinion that in the Diaspora it’s forbidden to eat new grain until the 18th of Nissan. Such is the ruling of the Tur and S”A Y”D 293:1. This ruling is also found in Kitzur S”A 172:1.
- S”A Y”D 293:1 and O”C 489:10, Kitzur S”A 172:1
- Sh”t Trumat HaDeshen 1:191 writes that it only takes 3 days for the plant to take root, while the Meiri Pesachim 55b writes that it takes two weeks. See further in Yalkut Yosef (Shaatnez UChaddash pg 441-2).
- Mishna Challah 1:1, Rambam Maachalot Asurot 10:2, Tur and S”A Y”D 293:1
- Sh”t HaRama 132(15) writes that one may be lenient regarding vessels which were used to cook Chaddash. This is quoted by the Magen Avraham 489:17. The Mishna Brurah 489:48 adds that one should only rely on this if it has been 24 hours since the vessels were used. This is also the ruling of Yalkut Yosef (Shaatnez UChaddash pg 439).
- The Taz Y”D 293:4 and Peni Yehoshua (Kuntres Acharon on Kiddushin) defend those who drink beverages that are produced from Chaddash grain. However, the Chacham Tzvi 20 and Yalkut Yosef (Shaatnez UChaddash pg 447) is strict.
- Gemara Kiddushin 38a, Yalkut Yosef (Shaatnez UChaddash pg 402, 425)
- Yalkut Yosef (Shaatnez UChaddash pg 417) is lenient, while Sh”t Shevet HaLevi Y”D 1:162 is strict. The Yalkut Yosef quotes other achronim who are lenient including the Shem Chadah (on Yeriyim Siman 169, pg 66d), Binat Adam (Siman 64), Keter Rosh (Siman 149) quoting the Gra, and Chasedei David (Menacot 10:7).
- In the Mishna in Kiddushin 36b there’s a dispute in the Mishna whether the prohibition of Chaddash applies to the Diaspora. Similarly there’s a dispute in Gemara Menachot 68b. Most Rishonim are stringent. These Rishonim include the Bahag (Orlah #6), Rif (Kiddushin 15a), Rosh (Kiddushin 1:62 and Sh”t HaRosh 2:62), Rambam (Maachalot Asurot 10:2), Ramban (Vayikra 23:14), Smag (Lavin 142), Smak (Siman 117), Meiri (Kiddushin 37a), Chinuch (Mitzvah 303), Ravyah (Pesachim 527), and Tur Y”D 293. Such is ruling of the S”A Y”D 293:2 and Kitzur S”A 172:2.
- However, the minority of Rishonim hold that Chaddash is only Derabbanan outside Israel. These Rishonim include the Or Zaruah 1:328, Rabbeinu Baruch (quoted in Teshuvot Harosh 2:1), and Raavan (according to Teshuvot Mishkenot Yaakov 64). In fact, the Or Zarua rules that because it is such a difficult halakha to keep, one may rely on the fact that it is a rabbinic law and therefore it would be permitted in cases of doubt since it is typically unknown when a certain product was harvested.
- Yalkut Yosef (Shaatnez UChaddash pg 446).
- Most Rishonim hold that Chaddash also applies to grain that was grown by non-Jews. These Rishonim include Tosfot (Avoda Zara 63b s.v. Ein), Ravyah (Pesachim Siman 527), Rosh (2:1) quoting the Rif (Kiddushin 16a), Avi Ezri (Siman 527), Sh”t HaRashba 1:177, and Meiri Pesachim 121b. However, a small minority of Rishonim (Tosfot Yeshanim (Rosh Hashana 13b) in name of the Ritzva, Sh”t HaRosh (beginning of Klal 2) quoting Rabbenu Baruch, Bach Y”D 493) hold that it doesn’t apply to grain grown by non-Jews. S”A Y”D 293:2 writes that Chaddash applies to grain of a non-Jew.
- Sh”t HaRosh 2:1 writes that in many years one doesn’t have to be concerned about grain one doesn’t know whether it is Chaddash or Yashan because the majority of the grain on the market is the old crop and furthermore there’s a double Safek (doubt), perhaps the grain one has was grown last year and even if it grew this year perhaps it took root before the 16th of Nissan. However, in this year there were pogroms before Pesach which prevented the (Jewish) farmers from growing grain before Pesach and so only a minority of the grain was grown before Pesach. The Rosh writes that as he looks towards heaven in the difficult times he was unable to forbid all the grain that year, but rather would answer the questioners that they should ask the farmers whether the majority of the grain was grown before Pesach and if so it’d be permitted. But nonetheless it’s better that the people should be uninformed and not sin intentional. This is quoted in the Tur Y”D 293.
- The former logic of relying on majority on grain that is from the old crop is widely accepted in the Rishonim including the Tosfot Kiddushin 36b s.v. Kol, Mordechai Menachot 501, Ravyah (Pesachim Siman 527), and Hagahot Maimoniot (Machalot Asurot 10:3). Tosfot (Kiddushin 36b) writes concerning wheat one could be lenient because the majority is planted before Pesach, but that by barley one should be strict because it’s growing season is after Pesach. The Ravyah (Pesachim Siman 527) writes that the majority of the beer was made from barley that was from the old grain and so one could be lenient. The Hagahot Maimon (Machalot Asurot 10:3) writes that the Maharam was strict regarding barley because of it’s late growing season. * The Trumat HaDeshen (Siman 191) writes that in years when there was snow on the ground and the farmers weren’t able to plant barley prior to Pesach that in countries that primarily drink beer one shouldn’t publicize the prohibition and it’s better that the masses are uninformed rather than intentionally sin. However, in countries that the primary drink is wine and barley is used infrequently one should publicize that barley which one doesn’t know whether it’s from the new grain or the old grain one should be strict. In the end, the Trumat HaDeshen rejects the double safek of the Rosh and says that it’s only considered a single safek and isn’t accepted if the minority of the grain is from the new crop.
- The Rama Y”D 293:3 rules like the Trumat HaDeshen that one should really only rely on the double safek if there’s also a majority of grain that’s from the old crop, but nonetheless, if the primary food and drink is from the new grain one shouldn’t publicize the prohibition.
- The Mishna Brurah 489:45 writes that the Achronim hold in Poland one shouldn’t be lenient concerning barley, oat, and spelt because the majority of these come from new grain, but one may be lenient regarding wheat and rye which a majority is from the old grain. The Mishna Brurah concludes that even though one can’t be strict on the masses one a righteous individual should be strict on himself.
- The Beiur Halacha (489:10 s.v. Af) writes that someone mistakenly think that if they are going to be strict about this prohibition, they have to be strict on everything entailed in the prohibition, on all grains, on drinks, and pots used for Chaddash, however, it’s much more proper to recognize that there’s what to rely on in many of the disputed cases such as drinks, pots used for Chaddash, and also the majority of many grains are grown before Pesach and so, one should endeavor to be strict at least in cases of certain Chaddash, but even in such cases one can’t rebuke the masses.
- The Yalkut Yosef (Shaatnez UChaddash pg 460) writes that one may be lenient if one doesn’t know if the grain one has is old grain in a place where the majority of the grain is from the old crop.
- Magen Avraham 489:17 writes this as a defense of those who aren’t strict about chaddash. This is also quoted by the Mishna Brurah 489:45.
- The Kitzur S”A 173:3 defends those who are lenient regarding Chaddash by saying that they rely on those who say the grain of a non-Jew is exempt from Chaddash. This is also quoted by the Mishna Brurah 489:45 who adds that if one relies on this one should be more strict regarding grain that was grown by Jewish farmers. However, the Yalkut Yosef (Shaatnez UChaddash pg 427), argues that since Shulchan Aruch holds that it also applies to grain of a non-Jew, Sephardim shouldn’t be lenient using this leniency.
- The Or Letzion Y”D 1:15 writes that one should only rely on this leniency on Shabbat and Yom Tov. However, Yalkut Yosef (Y”D 293:31, Hilchot Chadash VeShatnez 293:31 pg 469) writes that the strict law is that this leniency is reliable in places where there’s no bakery that offers old grain.
- Yalkut Yosef (Y”D 293:34, Hilchot Chadash VeShatnez 293:34)