At issue is whether the Reds are exempt from paying tax on the purchase of the promotional items.
Attorneys for the Reds argue they don't have to pay tax because they resell the promotional items as part of the ticket package.
Ohio law exempts companies from paying tax on items they buy to resell.
The state tax commissioner says the promotional items should be taxed because the Reds bought the items as giveaways and they aren't selling them with the tickets.
The state Supreme Court held oral arguments Wednesday morning. A decision is not expected for several weeks.
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