He Says a Priest Abused Him. 50 Years Later, He Can Now Sue.

Major institutions across New York State, from the Catholic Church to the Boy Scouts of America to elite private schools, are bracing for a deluge of lawsuits now that adults who said they were sexually abused as children will be entitled to pursue formal legal action.

New York joined more than a dozen states this year in significantly extending statutes of limitations for filing lawsuits over sexual abuse. Previously, the state had required that such suits be filed before a victim’s 23rd birthday.

Under the new law in New York, the Child Victims Act, which was approved by the Legislature in January, accusers will be able to sue until they are 55.

The new law includes a one-year period, known as a look-back window, that revives cases that had expired, in many instances decades ago, under previous statutes of limitations.

The one-year period begins on Wednesday, and the impact could cause major financial stress for many institutions in New York, including the state’s eight Catholic dioceses, which have faced a series of scandals involving abuse by clergy.

Some of the most prominent lawyers specializing in child sex abuse each have hundreds of cases to be filed as soon as the window opens, raising the prospect of overloading courts.

“It’s unlike anything we’ve ever seen,” Jason Amala, a lawyer representing abuse survivors, said of the calls that have inundated his firm, including some from victims who were telling another person about their abuse for the first time.

Lawmakers in New York had tried and failed for well over a decadeto expand the state’s statutes of limitations, which were regarded as among the most restrictive in the country. “We used to call New York a ‘shut down state,’” Mr. Amala said.