The New Orleans Aviation Board could decide Monday what company will get a half-billion-dollar contract to construct a new terminal at Louis Armstrong International Airport. Whatever the board decides, however, a dispute between the two firms bidding on the project could very well end up in court.

The process of selecting a contractor is tied up in legal arguments between the two joint ventures vying for the project, Parsons Odebrecht and Hunt Gibbs Boh Metro, over whether an 11-person evaluation committee properly rated the two plans.

The center of the dispute, which will be up to the Aviation Board to sort out, is whether the first of two evaluations done by the committee, which resulted in a tie, was handled properly. A second question is whether, if Hunt Gibbs Boh Metro should have won that evaluation, as it contends, it should now be awarded the contract despite the evaluation committee’s decisive swing toward Parsons Odebrecht in the second round of scoring.

The proposals by Parsons Odebrecht, a longtime partnership between firms from California and Brazil, and Hunt Gibbs Boh Metro, a joint venture between an Indianapolis firm and three local companies that joined forces specifically to bid on the airport contract, have already been through two rounds of evaluation by the committee.

That group gave both bidders identical total scores in the first round before recommending Parsons Odebrecht the next time it met.

On the initial evaluation, the 11 members of the evaluation committee gave each joint venture a total of 999 points out of a maximum of 1,100 — 100 points for each of the committee members. On the second round of evaluations, held to break the tie, Parson Odebrecht’s score increased slightly to 1,002 while Hunt’s score fell sharply to 956.

Hunt Gibbs Boh Metro then filed a protest saying it should have won outright in the first round.

That protest says the Hunt group received too low a score in one category — participation by businesses owned by women and minorities, known as disadvantaged businesses — due to what the company says was a technical error in certifications.

It says Hunt also was not given proper credit for the price of its proposal. The type of contract the airport is using asked both companies to use the entire $546 million budget for the project, but according to an analysis by airport officials, the Hunt proposal envisioned spending about $14 million more of the budget on actual construction — as opposed to other costs, such as profit and overhead — than Parsons Odebrecht. Therefore, Hunt contends, its proposal should have been rated higher in that category, but some committee members’ scores did not reflect that.

In response, Parsons Odebrecht argued that Hunt Gibbs Boh Metro should not even be considered qualified for the contract because of the issue with the disadvantaged business certification of Metro Services Group, one of the partners in the venture. The Parsons response also claimed the supposed price differential represented an “apples to oranges” comparison because the two groups may have put some costs in different categories in their proposals.

But even if Hunt Gibbs Boh Metro was due additional points on price and disadvantaged business status, the Parsons response argued, those changes still would not be enough to make it the committee’s recommendation, given the difference in scores from the second, tie-breaking round.

The Hunt protest “is fatally flawed and must be rejected,” according to Parsons.

In a supplementary response, Hunt reiterated its points, arguing the price criteria were clearly spelled out and the disadvantaged business certification was not, meaning its scores in both categories should be adjusted.

Hunt Gibbs Boh Metro further argued that those two categories represented objective criteria that did not give the members of the committee room to make judgments. Parsons Odebrecht, on the other hand, said committee members were entitled to score the two bids however they saw fit.

The Aviation Board will have to decide whether to accept the Hunt Gibbs Boh Metro protest and, potentially, which company should get the contract. Whatever it decides, though, both joint ventures would have the ability to challenge the decision in court.

The drop in Hunt Gibbs Boh Metro’s score was largely due to significant downgrades by several committee members, including Deputy Mayor Cedric Grant and two city employees who work under him. In their revised evaluations, those officials cited concerns that the person who would be managing the project for the Hunt joint venture had never headed up a similar type of contract, and that the Parsons Odebrecht proposal would end up giving work to more small contractors beyond those directly involved in the joint venture.

Grant, Mayor Mitch Landrieu’s top deputy for infrastructure and capital projects, worked for Parsons about 10 years ago. City officials have said his previous employment does not violate any ethics laws, and that his experience with similar contracts gave him important insight into the evaluation.

Follow Jeff Adelson on Twitter, @jadelson.