Gov. Philip D. Murphy of New Jersey has signed into law a measure narrowing access to government records, angering activists who have argued that the legislation will allow public corruption to flourish.

The new law, which Mr. Murphy, a Democrat, described as an effort to modernize the state’s existing Open Public Records Act, will give the government more discretion on what information it will release, and when.

Budgets, bills, vouchers and contracts — previously ordered to be readily available — now may be delayed if they’re more than two years old. People or organizations who successfully sue for access to government documents will have a more difficult time being reimbursed for their lawyers’ fees. And deadlines for the government to fulfill requests for public records — already routinely violated, with little repercussion — will be greatly extended.

The legislation angered the American Civil Liberties Union, the League of Women Voters of New Jersey and the New Jersey Foundation for Open Government. The New Jersey Press Association and the state chapter of the Society of Professional Journalists contended that public documents are key to detecting and preventing manipulation of money, public policy and other taxpayer interests.

In a statement on Wednesday, the governor acknowledged the opposition to the law.

“I know that this decision will disappoint many members of the advocacy community, including a number of social justice, labor, and environmental organizations, among others,” Mr. Murphy said.

But he pushed back against arguments that the legislation would create new opportunities for malfeasance.