In conditional statements, the definite article ה will not come on the subject when it uses the word כי (or any word that means if) - וכהן כי יקנה נפש (But if a priest buy any soul)⁴⁰⁹ אשר נשיא יחטא (When a ruler sins)⁴¹⁰. (Unless it comes on the subject with the phrase word אשר - האיש אשר יעשה בזדון - And the man that does presumptuously⁴¹¹).

footnotes: ⁴⁰⁹ Leviticus 22:11. ⁴¹⁰ Leviticus 4:22. ⁴¹¹ Deuteronomy 17:12.

And the reason for this is that if the subject is also a proper noun, after it speaks about it in a possible way and in a possible time, it is nevertheless impossible to individualize it. For example, even though הנשיא is a proper noun, it is not possible to say אם הנשיא יחטא, because in times of the future, there will be many leaders and we will not able to individualize which ones will sin. And when it writes אם הכהן המשיח יחטא (if the anointed priest shall sin)⁴¹², there is a homiletical interpretation.

footnotes: ⁴¹² Leviticus 4:3.

However, whenever it talks afterwards about the subject in a way of decision – the definite article ה will come according to its rules.

Leviticus 4:3 says,אם הכהן המשיח יחטא לאשמת העם והקריב על חטאתו אשר חטא פר בן בקר תמים ליהוה לחטאת(if the anointed priest shall sin so as to bring guilt on the people, then let him offer for his sin, which he has sinned, a young bullock without blemish to the LORD for a sin-offering), using the words הכהן המשיח for “the anointed priest” with the definite articlesה*, thus breaking Rule 179. The homiletical interpretation is that this indicates that he is the high priest⁴¹³.*

footnotes: ⁴¹³ Malbim, HaTorah v’HaMitzvah Vayikra 202.