G.R. No. 152438 - Ayson vs. Vda. de Carpio

Petitioner was the owner of three (3) parcels of land in Manibang, Porac, Pampanga, which were covered by Transfer Certificates of Title (TCT) Nos. 147096-R, 155262-R, and 155362-R.
On August 29, 1980, petitioner mortgaged these properties to the Philippine National Bank, Angeles City Branch.
Following the mortgage, the bank foreclosed on the properties. After the redemption period lapsed, the original TCTs were cancelled, and new titles were issued in the bank’s name on May 14, 1985, namely:

On April 14, 1999, the property covered by TCT No. 220195-R was sold by the bank to the respondent, with a new title issued in her name (TCT No. 466519-R).
Petitioner filed a complaint on October 22, 1999, before the Regional Trial Court (RTC) of Angeles City, seeking:

Issued demand letters dated December 29, 1999, urging petitioner to vacate the premises covered by TCT No. 466519-R
Filed a separate ejectment complaint with the Municipal Trial Court (MTC) on March 7, 2000, demanding petitioner’s vacation of the property along with damages.

The MTC rendered a decision on June 23, 2000, ordering petitioner to vacate the subject property.
On appeal from the MTC decision, the RTC affirmed—with modifications—the ejectment ruling.
Petitioner interposed an appeal to the Court of Appeals (CA) challenging:

The jurisdiction of the trial court based on the contention that it ventured into issues not alleged in the original complaint
The sufficiency and nature of the pleadings in framing the cause of action
The propriety of evidentiary matters, especially regarding the alleged non-receipt of demand letters.

Demonstrated petitioner’s continued unlawful possession following foreclosure and non-redemption of the property
Substantiated respondent’s acquisition of a better right to possession via a subsequent sale between her and the bank

Petitioner, while contesting the trial court’s jurisdiction on appeal, further argued:

That the complaint was defective for not averring sufficient details on how the alleged dispossession occurred and the actual receipt of the demand letters
That the complaint, by omitting certain details, should have been considered a different cause of action (accion publiciana rather than an ejectment leading to unlawful detainer)
That her subsequent participation in the trial on its merits should estop her from raising jurisdictional defects at the appellate level.

Whether defects in the original complaint are deemed waived when the parties proceed to trial and evidence is subsequently introduced to establish a cause of action not originally alleged.
Whether the Municipal Trial Court (MTC) had proper jurisdiction over respondent’s ejectment complaint given that the complaint’s content and pleading defects might indicate an alternative cause of action (accion publiciana or unlawful detainer).
Whether petitioner’s voluntary participation in the trial on the merits estopped her from later contesting the trial court’s jurisdiction.
Whether the late raising of issues—specifically the non-receipt of the demand letters—is procedurally barred and inconsistent with the doctrine of due process in appellate proceedings.