The S.C. Supreme Court could settle a running feud over who controls the state’s $27 billion pension fund, as it considers whether Treasurer Curtis Loftis is breaking the law by refusing to write a check for an approved investment.

The court on Friday granted the Retirement System Investment Commission’s request to take its case against the first-term Republican treasurer. A hearing is 8:30 a.m. Tuesday.

The commission that oversees the pension portfolio argues Loftis is attempting an illegal power grab by refusing to fund an investment he and his fellow board members approved last November. It is asking the high court to act quickly, saying the state will default if $11.7 million isn’t paid Tuesday.

Loftis, the board’s only elected member, repeatedly notes that state law makes him the official custodian of the money. But the commission contends that’s an administrative task — that he has no special authority over an investment after it’s properly approved. The lawsuit filed Thursday cites a November 2011 opinion from the South Carolina attorney general’s office, as well as similar cases in other states, to back up the commission’s argument.

The court has directed Loftis to file a response by Monday morning. Loftis has said he won’t sign off until he gets more assurances the state won’t overpay on fees. He argues the current paper trail — which includes copies of emails — isn’t sufficient, so he created a document he wants the commission’s attorneys to sign.

“My requests to the investment commission have been straightforward and simple,” he said Friday. “These games are not productive especially when the funds of working people are at stake.”

But while the case involves a spat over a particular investment, the commission hopes the state’s high court settles once and for all questions about Loftis’ role and responsibilities with the fund, which provides the pensions of South Carolina’s public workers.