"The use of riders is prevalent and customary in the Congress of the United States, as there are no legal or other limitations on their use.
Riders are most effective when attached to an important bill, such as an appropriation bill, because to veto or postpone such a bill could delay funding to governmental programs, causing serious problems." (via Wikipedia)
If we truly want to address the issue of "pork", and cut back on unnecessary spending, we need to address and abolish riders that allow unrelated measures to be passed in a bill.