[2] He was the presiding judge in a number of cases involving high-profile defendants, including E. Jean Carroll v. Donald J. Trump, Virginia Giuffre v. Prince Andrew, United States v. Bankman-Fried, and trials of Al Qaeda terrorists such as Ahmed Ghailani.

[7]The New York Times reported that Kaplan's ruling could set a precedent for the cases of other Guantanamo captives, who, like Ghailani, are transferred to the civilian justice system.

On January 25, 2011, Kaplan sentenced Ghailani to life and called the attacks "horrific" and saying the deaths and damage they caused far outweighs "any and all considerations that have been advanced on behalf of the defendant."

Eric Spoutz, an art dealer, pleaded guilty to one count of wire fraud related to the sale of falsely attributed artwork accompanied by forged provenance documents.

Kaplan granted Chevron's motion barring enforcement of an almost $10 billion judgment awarded by the Ecuadorian courts against the company in February 2011.

Kaplan found there to be overwhelming evidence that the Ecuadorian verdict was the result of a criminal conspiracy spear-headed by the plaintiff's lead attorney, Steven Donziger.

[10][11] Donziger was unable to satisfy the contempt fine and restitution award so Kaplan ordered he surrender certain personal items of his such as cell phones and computers.

When the SDNY US Attorney's Office declined to pursue the case in August 2019, Kaplan appointed a private law firm, Seward & Kissel to prosecute Donziger.

[13] At the hearing, Alberto Guerra, a former Ecuadorian judge, testified for Chevron, claiming Donziger bribed him and others to win the case by fraud.

[14] According to The Intercept, Kaplan has written favorably about Chevron and "bypassed the standard random assignment process and handpicked someone he knew well, U.S. District Judge Loretta Preska, to oversee the case being prosecuted by the firm he chose.

In March 2021, the Second Circuit heard another appeal by Donziger against prior court orders made by Kaplan in the civil contempt action brought by Chevron.

The appeals court found the order barring Donziger from financing his legal defense by selling shares in any future award to be unenforceable.