The Georgia Government Transparency and Campaign Finance Commission (formerly the Georgia State Ethics Commission) appeals from an order issued by the Fulton County Superior Court ruling that the expiration of the applicable statute of limitation barred the Commission’s preliminary investigation into whether reasonable grounds existed to believe that State Mutual Insurance Company and Admiral Life Insurance Company (the Companies) made contributions to an election campaign for public office in violation of the Ethics in Government Act (the Act) (OCGA § 21-5-1 et seq.). For the reasons that follow, we find that the court had no jurisdiction to issue the ruling because it was entered after a final order entered in the case at a prior term of the court. Accordingly, the court’s ruling on the statute of limitation was null and void and must be vacated.
This appeal arises from a preliminary investigation initiated by the Commission based on its finding of probable cause to investigate contributions made in 2008 by the Companies to a political action committee which contributed to the campaign of former Georgia Insurance Commissioner, John Oxendine, for the office of Governor of Georgia. During the pendency of the Commission’s investigation into possible violations of the Act, the Companies filed a complaint on May 28, 2010, in the Fulton County Superior Court.1 The complaint sought a declaration that the Commission lacked authority under the *481Act to proceed with the preliminary investigation of the Companies, and sought temporary and permanent injunctive relief barring the Commission from proceeding with the investigation and barring the issuance of subpoenas pursuant to the Act in support of the investigation. After a hearing, the court entered an order on July 16, 2010, captioned as its “Final Order” in favor of the Commission. With respect to the requested declaratory and injunctive relief barring the Commission’s investigation and subpoenas issued under the Act, the court’s order denied temporary injunctive relief and further ruled:
Having considered the pleadings, motions, arguments, the entire record and applicable law, the Court finds OCGA [§] 21-5-6 (a) (5) specifically vests in the State Ethics Commission the power to find probable cause to initiate hearings and similarly to issue subpoenas in connection with its investigation of possible violations.
The court’s “Final Order” also included a statement that the clerk of the court was “ordered to reflect upon the record that this case is now ‘inactive’ and ‘disposed.’ ”
After the court entered the July 16, 2010 final order, the Companies filed a pleading on August 2, 2010, denominated as a motion for a new trial. Although called a motion for new trial, the motion asked the court to reconsider legal rulings in the final order and to expressly rule in favor of the Companies on all the issues including declaratory and injunctive relief. Without any ruling on the motion, the investigation recommenced before the Commission, and on or about March 2011 the Companies for the first time raised a statute of limitation defense before the Commission. On March 1, 2011, the Commission issued an order in the investigation stating that the statute of limitation issue raised by the Companies “is hereby severed from the... [investigation proceeding] so that it can be decided by the Fulton Superior Court in its pending action.” On April 25, 2011, the Companies filed the Commission’s order in the prior Court action, followed by a “Motion for Determination of Applicable Statute of Limitation” filed in the same action on June 7, 2011, by which the Companies sought a ruling from the court that the statute of limitation applicable to the Commission’s investigation had expired and the investigation was barred. On March 27, 2012, the court issued an order it captioned as the second “final order” in the same action. The second final order, in effect, vacated the final order issued by the court on July 16, 2010; granted the Companies’ June 7, 2011 motion on the statute of limitation; and ruled that the Commission’s investigation was barred by the applicable statute of limitation. As to the “motion *482for new trial” filed by the Companies on August 2, 2010, the second final order ruled that it was granted in part by the court’s ruling on the statute of limitation, and otherwise denied as moot.
The Commission claims that, despite having sought a ruling from the superior court on the statute of limitation issue, the court had no jurisdiction to enter the second final order ruling on the statute of limitation issue first raised by the Companies in the June 7, 2011 motion. We agree that, after entering a final order in the action on July 16, 2010, the court had no jurisdiction to consider the statute of limitation issue raised for the first time in a subsequent term of the court.
We conclude that the court’s July 16, 2010 order was a final and appealable judgment in the action which resolved all the issues raised in the Companies’ complaint and reflected that the case was disposed of and no longer pending in the court. See OCGA § 5-6-34 (a) (1). “Whether an order is final and appealable is judged by its function and substance, rather than any magic language.” (Citation and punctuation omitted.) Rhymes v. East Atlanta Church of God, Inc., 284 Ga. 145, 146 (663 SE2d 670) (2008). An order finally adjudicates a pending issue when it does so expressly or by necessary implication. Id. at 146-147; Fraser v. Moose, 226 Ga. 256, 258-259 (174 SE2d 412) (1970).
The court’s order was captioned as a “Final Order” and directed that the Clerk mark the case “Disposed.” In the order, the court (1) expressly denied the temporary injunctive relief sought in the complaint, and (2) entered a ruling that by necessary implication denied the remaining declaratory and permanent injunctive relief sought in the complaint. As to declaratory and permanent injunctive relief, the Companies sought an order from the court: (1) declaring that various portions of the Act showed the Commission lacked statutory authority under the Act to proceed with the investigation initiated on the Commission’s probable cause finding, and (2) permanently barring the Commission from proceeding with the investigation and issuing subpoenas pursuant to the Act. As to those issues, the court ruled:
Having considered the pleadings, motions, arguments, the entire record and applicable law, the Court finds OCGA [§] 21-5-6 (a) (5) specifically vests in the State Ethics Commission the power to find probable cause to initiate hearings and similarly to issue subpoenas in connection with its investigation of possible violations.
By this ruling, the court clearly decided that the Commission had statutory authority under the Act to proceed with the preliminary *483investigation it initiated against the Companies on a finding of probable cause, and to issue subpoenas in support of the investigation. By necessary implication, this ruling constituted a denial of the declaratory and permanent injunctive relief sought by the Companies on every ground on which the relief was sought. Fraser, 226 Ga. at 258-259; Rhymes, 284 Ga. at 146-147. Moreover, the court’s “Final Order” was preceded by a hearing at which the Companies were allowed to put up their entire case, calling witnesses and arguing that the court should find that the Commission’s investigation was outside the authority of the Act and should be enjoined. The court’s rulings, express and by necessary implication, show that the July 16, 2010 order was a final order appealable by a notice of appeal filed within 30 days of the order’s entry. OCGA §§ 5-6-34 (a) (1); 5-6-38 (a).
The Companies did not file a notice of appeal from the July 16, 2010 final order, but filed a pleading on August 2, 2010, designated as a motion for a new trial. A valid motion for new trial maintains the trial court’s power over its final judgment during the pendency of the motion, and extends the time for filing a notice of appeal until 30 days after the court’s entry of an order granting, overruling, or otherwise finally disposing of the motion. OCGA § 5-6-38 (a); Bagley v. Robertson, 265 Ga. 144, 146 (454 SE2d 478) (1995). “Amotion for a new trial is a proper means of seeking a retrial or reexamination, in the same court, of an issue of fact, or of some part or portion thereof, after decision by a jury or a decision by the court thereon.” Bank South Mtg., Inc. v. Starr, 208 Ga. App. 19 (429 SE2d 700) (1993). It is not a proper means to challenge a court’s judgment solely on issues of law. Id. at 19-20. Here, the Companies’ “motion for new trial” pleading did not challenge factual findings but only the court’s legal conclusions. Because the substance of the pleading shows that it sought the court’s reconsideration of legal rulings, it was not a valid motion for a new trial and did not extend the court’s control over the July 16,2010 final order or the time for filing a notice of appeal. Pillow v. Seymour, 255 Ga. 683 (341 SE2d 447) (1986); Houston County v. Harrell, 287 Ga. 162 (695 SE2d 29) (2010) (motion for reconsideration does not extend the time in which appeal may be filed).
Nevertheless, because the August 2, 2010 motion seeking reconsideration of the court’s July 16, 2010 final order was filed during the same term of the Fulton County Superior Court in which the final order was entered (OCGA §§ 15-6-3(3); 15-6-19), the motion remained within the breast of the court, even after the time for appealing the final order expired, and even after the expiration of the term of court. Where not based on a jury verdict, a trial court has inherent power, unchanged by the Civil Practice Act, to change its final judgment during the term of court in which it is rendered. Maxwell v. Cofer, 201 *484Ga. 222, 226 (39 SE2d 314) (1946); Ammons v. Bolick, 233 Ga. 324, 325 (210 SE2d 796) (1974). As to change to a final judgment at subsequent terms of court, the general rule is that “a court cannot set aside or alter its final judgment after the expiration of the term at which it was entered, unless the proceeding for that purpose was begun during the [original] term.” Miraglia v. Bryson, 152 Ga. 828 (111 SE 655) (1922). This is a general common law rule which applies in civil as well as criminal cases. See Platt v. State, 200 Ga. App. 784-785 (409 SE2d 878) (1991); Moon v. State, 287 Ga. 304, 306 (696 SE2d 55) (2010) (Nahmias, J., concurring). Where no such proceeding is filed during the term in which the final judgment is entered, the trial court has no jurisdiction in the case after the expiration of the term, and any order entered after expiration of the term is null and void. Robinson v. Kemp Motor Sales, Inc., 185 Ga. App. 492, 493 (364 SE2d 623) (1988); Long v. Long, 247 Ga. 624 (278 SE2d 370) (1981).
Although the court retained jurisdiction at subsequent terms of court to consider the August 2, 2010 motion for purposes of changing its July 16, 2010 final order, the court had no jurisdiction to consider the June 7, 2011 motion for this purpose. The June 7, 2011 motion, which raised the statute of limitation issue for the first time, was filed at a term of court subsequent to the court term in which the July 16, 2010 final order was entered. In the second final order entered on March 27, 2012, which granted the June 7, 2011 motion and changed the July 16, 2010 final order, the court considered its ruling on the June 7,2011 motion to be a partial grant of the August 2,2010 motion. In effect, for the purpose of changing the July 16,2010 final order, the court claimed jurisdiction to rule on the June 7, 2011 motion as an amendment to the pending August 2, 2010 motion, which was filed in the original court term and over which the court retained jurisdiction. But even if the June 7, 2011 motion could be considered an amendment to the August 2, 2010 motion, because the June 7 motion set forth a new reason for changing the final order and was filed after the term in which the final order was entered, the court had no jurisdiction to consider it as a basis to change the final order. Matthews v. State, 295 Ga. App. 752, 753-754 (673 SE2d 113) (2009) (where a motion to change the final judgment was filed during the original court term, new claims added by amendment to the motion during a subsequent term did not give the court jurisdiction to change the final judgment). Because the court lacked jurisdiction, its ruling on the statute of limitation issue raised in the June 7, 2011 motion was null and void.
In his separate dissent, Judge Dillard argues that, even if the court’s July 16, 2010 order was a final order, and therefore the court’s March 27, 2012 order on the statute of limitation issue was void for *485lack of jurisdiction, the Court of Appeals should sua sponte invoke the doctrine of judicial estoppel to preclude the Commission from asserting that the court’s order was void. It does not appear that any Georgia appellate court has raised the doctrine of judicial estoppel on its own motion in an appeal, although, where the doctrine was not raised by the parties, we have declined to address it. Glover v. Ware, 276 Ga. App. 759, 761 (624 SE2d 285) (2005) (“Because the issue has not been raised by the parties, we do not address whether the doctrine of judicial estoppel applies in this case.”)2 Judicial estoppel was not raised by a party below or on appeal in this case, nor was it ruled on by the trial court. Assuming, without deciding, that the issue could be invoked sua sponte in a proper case on appeal, judicial estoppel is not available in this case to prevent the Commission from asserting that the court’s March 27, 2012 order was void for lack of jurisdiction. “A final judgment cannot be amended at a subsequent term. . . . Jurisdiction of the subject matter of a suit cannot be conferred by agreement or consent, or be waived or based on an estoppel of a party to deny that it exists.” (Punctuation omitted; emphasis supplied.) Redmond v. Walters, 228 Ga. 417 (186 SE2d 93) (1971).
Furthermore, judicial estoppel protects the integrity of the judicial process by preventing a party from manipulating the process to gain an unfair advantage. Dillard-Winecoff, LLC v. IBF Participating Income Fund, 250 Ga. App. 602, 602-604 (552 SE2d 523) (2001). Judicial estoppel does not apply because the Commission took no action designed to give it an unfair advantage. In response to the Companies’ motion to dismiss the Commission’s preliminary investigation on the ground that the statute of limitation had expired, the Commission issued an order which assumed that no final order had been entered in the prior superior court case, and which severed the statute of limitation issue from the pending preliminary investigation “so that it can be decided by the Fulton Superior Court in its pending action.” Although the Commission’s order invited the court to decide the statute of limitation issue, the Commission, which was subsequently represented before the court by the Georgia Attorney General’s office, candidly informed the court that its July 16, 2010 final order divested the court of jurisdiction to address the issue, and that the Commission’s order erroneously assumed the contrary. The court rejected the Commission’s position and issued a second final *486order on March 27,2012, ruling on the statute of limitation issue. The Commission did not attempt to manipulate the process to its advantage, but correctly informed the court about the effect of the final order and argued that the court should decline the invitation to rule. Contrary to the dissent, the Attorney General’s assertion of the same position on behalf of the Commission on appeal is not “judicial gamesmanship” or “an attempt to play the courts for fools.”
Judgment vacated.
Ellington, C. J., and Phipps, P. J., concur. Barnes, P. J., and Doyle, P. J., concur in judgment only. Dillard and Boggs, JJ., dissent.In addition to naming the Commission as a defendant in the superior court action, the former chairman of the Commission, James C. Gatewood, and a former member of the Commission, Patrick N. Millsaps, were named as defendants in their official capacities. All three defendants brought this appeal and are collectively referred to in this opinion as the Commission.
The Fifth Circuit has concluded it could invoke the doctrine of judicial estoppel sua sponte on appeal in an extraordinary case, but found that, “[ajbsent a flagrant threat to the judicial process, however, we will not disregard the waiver produced by a failure to plead judicial estoppel in conformity with Federal Rule of Civil Procedure 8 (c).” American Bank v. C. I. T. Constr., Inc., 944 F2d 253, 258 (5th Cir. 1991); see OCGA § 9-11-8 (c).