Idaho Code § 35-104
Each adjoining land owner, unless both otherwise agree, or unless other arrangements have heretofore been made, must construct and keep in repair that half of the line fence between their respective tracts of land that is to his left when he is standing on his own land facing the other; unless the owner of one (1) of said tracts chooses to allow his land to be uninclosed: provided, that one (1) party may, for his own convenience, strengthen, or render hog-tight, the whole or any part of said fence by stretching one (1) or more additional wires thereon or otherwise; in which event the other shall not be liable for his proportion of the additional cost. Provided further, if one (1) of the parties shall render such fence hog-tight and the other shall at any time use his field for the pasture of hogs, sheep or goats, without a herder, such other shall become liable as a joint user or owner and shall, upon demand of the party building the hog-tight fence, pay his just proportion thereof. In case viewers are appointed, as provided in section 35-106, Idaho Code, the report of such viewers must be in conformity with this section.
Idaho Code § 35-104