Partisanship (noun)

1. Strong and sometimes unfair support for a particular political party, group, or cause.
2. The practice or principle of showing strong and sometimes unfair support for a particular political party, group, or cause.

Origin:

Early 19th century: from french parti + -anship, on the pattern of words such as sportsmanship.

Examples:

1. The decision was criticized as being motivated by partisanship.
2. The hearing was marred by partisanship.
3. The report was criticized for its partisanship.
4. The candidate was accused of partisanship.
5. The bill was criticized for its partisanship.