FOR A FLASHING neon example of how politics takes precedence over policy in our government, one need look no further than the 11-page list of special exemptions to the state sales tax.

The fact that the list has survived intact for so long, and that most politicians are afraid to even whisper about reforming it, speaks volumes to the influence its beneficiaries have at the State House. But it also suggests that most people aren’t aware of just how little sense it makes.

What’s striking about our list of sales tax exemptions is not its size but how many of the items on it seem to serve no legitimate state interest or, if they do, to do so in such a selective way.

This begins with the category of exemptions most people would agree makes sense: raw materials. The idea is that if you tax the cotton that goes into making thread and the thread that goes into making cloth and the cloth that goes into making a pair of blue jeans, the effective tax rate the consumer pays on that pair of blue jeans is no longer the intended 5 percent, but 20 percent. That means consumers in South Carolina are paying higher taxes than intended, and it means that consumers in other states won’t even consider buying those South Carolina jeans.

The problem with our raw materials list is that it is so incomplete. The most obvious raw material that missed out on the exemption is construction materials — unless the construction materials are to used for a factory hog or chicken farm, in which case they are exempt. But there are others, as well. The list is long on exemptions for traditional S.C. businesses, from agriculture and textiles to power production. But there’s no exemption for the raw materials used by pharmaceutical companies, or other newer industries. (To view the list of exemptions, go to www.scstatehouse.net/code/t12c036.htm and scroll down to Section 12-36-2120.)

Other inconsistencies have less to do with which businesses have deep pockets than with the special interests of legislators.

Buy a book for pleasure, or for work, and you’ll pay the state’s 5 percent sales tax on it — unless it’s a Bible, in which case you won’t. Buy any book for school, and there’s no tax. (Does this mean you get money back if you buy a Bible for a religion class at school? Never mind.)

There’s no tax on products purchased by charitable hospitals that primarily serve children, but the tax is charged on hospitals that serve adults, and on all other charitable organizations.

Non-profit organizations don’t have to pay a tax on prepared food they buy from other non-profits, or from companies that use the labor of “the homeless or the needy.” But they’re taxed if they buy the food from for-profit businesses.

Syringes, bags, tubing and other disposable medical supplies used to deliver prescription drugs intravenously aren’t taxed if they’re used by a patient at home; they are taxed if they’re used in a hospital or nursing facility.

Eyeglasses are taxed; hearing aids aren’t.

We tax groceries, unless you buy them directly from the farmer who grew them, in which case they’re exempt.

Hotel rooms are taxed; vacation time shares are not.

There’s no tax on an extended service contract for a motor vehicle, but no exemption for the extended service agreement on your computer.

We’re even inconsistent with government purchases. Unlike most states, we charge a sales tax when government agencies purchase products — except when they’re buying war memorials and monuments, or when they’re purchasing plants or animals.

An out-of-state soldier stationed in South Carolina doesn’t pay sales tax on a new car or motorcycle; a soldier from South Carolina does. And both pay taxes if they buy a truck.

That’s not the only preference we reserve for folks from other states.

Asphalt products aren’t taxed if they’re used to pave roads in another state. And they aren’t taxed if they’re purchased by contractors in-state who are doing work for the U.S. government. But if those same products are used to pave state or county or city roads, they’re taxed.

And non-South Carolinians don’t have to pay taxes on any of the products South Carolinians pay taxes on if those products are shipped directly to them in their home states.

Exemptions have a legitimate place in a tax code. They can be used to avoid taxing the same activity or product twice, as some of our sales tax exemptions do. They can be used to modify the overall balance of a tax system, for example giving an income tax break to the poor or letting groceries go untaxed, in order to make a system less regressive. They can be used to encourage certain behaviors, as we do when we give income tax breaks for retirement savings or for having children.

Or they can be used at a whim, as too many of ours are.

Ms. Scoppe can be reached at cscoppe@thestate.com.