The only elements that the police need to prove under G.S. 20-138.7 (A1) are:
1. You possessed an open alcoholic beverage, and
2. You where in a motor vehicle, and
3. The vehicle was on the roadway.
It would be rather difficult to defend these elements, if the officer observed the above set of facts. If any of these elements were not present then you would have a defense.
Luckily you did not register any alcohol in your blood, because that would activate other sub-sections of this statue.
Section (g) of the statue outlines the above elements to prove the violation:
" (g) In any prosecution for a violation of subsection (a1) of this section, the pleading is sufficient if it states the time and place of the alleged offense in the usual form and charges that (i) the defendant possessed an open container of alcoholic beverage in the passenger area of a motor vehicle while the motor vehicle was on a highway or the right-of-way of a highway, or (ii) the defendant consumed an alcoholic beverage in the passenger area of a motor vehicle while the motor vehicle was on a highway or the right-of-way of a highway."
Of interest to you might be that a violation of (A1) does not qualify, as a moving violation therefore, there will be no driving point added to you record.
Finally, the penalty for a violation under G.S. 20-138.7 (A1) is considered an infraction and under G.S. 20-176, an infraction is punishable by a fine of not more than $100.00 and therefore, not a criminal offense.
I have included sections of G.S. 20 from the North Carolina laws above and below for your review.
(e) Punishment; Effect When Impaired Driving Offense Also Charged. - Violation of subsection (a) of this section shall be a Class 3 misdemeanor for the first offense and shall be a Class 2 misdemeanor for a second or subsequent offense. Violation of subsection (a) of this section is not a lesser included offense of impaired driving under G.S. 20-138.1, but if a person is convicted under subsection (a) of this section and of an offense involving impaired driving arising out of the same transaction, the punishment imposed by the court shall not exceed the maximum applicable to the offense involving impaired driving, and any minimum applicable punishment shall be imposed. Violation of subsection (a1) of this section by the driver of the motor vehicle is a lesser-included offense of subsection (a) of this section. A violation of subsection (a) shall be considered a moving violation for purposes of G.S. 20-16(c).
Violation of subsection (a1) of this section shall be an infraction and shall not be considered a moving violation for purposes of G.S. 20-16(c).
Part 12. Sentencing; Penalties.
§ 20-176. Penalty for misdemeanor or infraction.
(a) Violation of a provision of Part 9, 10, 10A, or 11 of this Article is an infraction unless the violation is specifically declared by law to be a misdemeanor or felony. Violation of the remaining Parts of this Article is a misdemeanor unless the violation is specifically declared by law to be an infraction or a felony.
(b) Unless a specific penalty is otherwise provided by law, a person found responsible for an infraction contained in this Article may be ordered to pay a penalty of not more than one hundred dollars ($100.00).
(c) Unless a specific penalty is otherwise provided by law, a person convicted of a misdemeanor contained in this Article is guilty of a Class 2 misdemeanor. A punishment is specific for purposes of this subsection if it contains a quantitative limit on the term of imprisonment or the amount of fine a judge can impose.
(c1) Notwithstanding any other provision of law, no person convicted of a misdemeanor for the violation of any provision of this Chapter except G.S. 20-28(a) and (b), G.S. 20-141(j), G.S. 20-141.3(b) and (c), G.S. 20-141.4, or a second or subsequent conviction of G.S. 20-138.1 shall be imprisoned in the State prison system unless the person previously has been imprisoned in a local confinement facility, as defined by G.S. 153A-217(5), for a violation of this Chapter.
(d) For purposes of determining whether a violation of an offense contained in this Chapter constitutes negligence per se, crimes and infractions shall be treated identically. (1937, c. 407, s. 137; 1951, c. 1013, s. 7; 1957, c. 1255; 1967, c. 674, s. 3; 1969, c. 378, s. 3; 1973, c. 1330, s. 34; 1975, c. 644; 1985, c. 764, s. 20; 1985 (Reg. Sess., 1986), c. 852, ss. 7, 17, c. 1014, s. 202; 1993, c. 539, s. 379; 1994, Ex. Sess., c. 24, s. 14(c).)
I hope this answers all of your questions.
I suggest if you decide to pay the fine, verify with the court first hand that the limit of the penalty is a civil fine of not more than $100.