As we begin this week a new cycle of Torah reading it is the perfect time to review some Halachot that pertain to Kriat Hatorah. Most people are aware that the proper distribution of the first three aliyot should be: Cohen receives the first aliya, a Levi is next and a Yisrael receives the third aliya. The Gemarah Gitin 59b explains that this Halacha is learned from one of several pesukim that indicate that we must show respect to the Cohen by giving him precedence in aliyot to the Torah. So, too, the Levi who holds a special place in the Mikdash and serves the Cohen should receive precedence over the ordinary Jew.
What should the order be in the event that a Cohen is not present at the reading of the Torah? In Gitin we are taught that if a Cohen is not present the package is dissolved. Rashi explains that the order of Cohen, Levi and Yisrael is seen as a package since the precedence given to the Levi is a function of the precedence the Cohen receives. When no Cohen is present the Levi loses his unique position as well.
As to the application of this halacha we find two understandings (both presented by Rashi in the name of his different teachers). One understanding is that the Levi only receives the second aliya if a Cohen has received the first aliya. Since the precedence of the Levi is dependent on precedence of the Cohen when no precedence is applied to a Cohen none should be given to the Levi. Therefore both the first and second aliyot should be given to a Yisrael.
A second understanding is that there is no requirement to give precedence to the Levi but a Levi may proceed the Yisrael. In all cases when calling up for the first aliya it should be stated that a Cohen is not present.
When a Levi is not present in the Beit Kneset the Cohen who received the first aliya receives the second aliya as well. Another Cohen or a Yisrael should not be called up in place of the Levi so as not to raise suspicion of the first Cohen’s qualifications as a Cohen.
Due to the concern lest we cause any suspicion in reference to a Cohen or Levi’s qualifications we may not at any time call up two Cohanim or Leviim consecutively. According to the Shulchan Aruch (Orach Chayim 135/10) we may call a second Cohen or Levi after a Yisrael has been called up. The accepted opinion amongst the Ashkenazik poskim is that a second Cohen or Levi can only be called up for Maftir.