The United States Conference of Catholic Bishops is promising a legal challenge to federal rules requiring health insurers and non-profit religious employers, such as hospitals and colleges, to provide free birth control to women.

The new rules were reaffirmed Friday by the Obama administration and go into affect Aug. 1.

The Department of Health and Human Services rejected a Roman Catholic Church request for an exemption for employees of Catholic hospitals, schools and charities, although they have a year to institute the change.

(GlobalPost reports: Obama grants church groups grace period on birth control)

Abortion rights opponents had challenged the rules, arguing that contraception violates the religious beliefs of some Americans, and that some forms of emergency contraception, including Plan B, are akin to early abortion, Kaiser Health News reported.

The bishops’ group "will fight this edict; they have no choice but to fight this edict," Kaiser quoted Sister Mary Ann Walsh, director of media relations for the bishops, as saying.

Two Catholic colleges — Belmont Abbey in North Carolina and Colorado Christian University — have already sued the government, arguing it violates their First Amendment and their religious freedom.

The Catholic Health Association, meanwhile, reportedly called Friday’s announcement "a missed opportunity to be clear on appropriate conscience protection."

The ruling satisfied abortion right proponents, however.

Planned Parenthood said it was "grounded in sound medical science and health policy and protects access to affordable birth control for millions of women, including women who are employed by a religiously affiliated hospital, university, or other religiously affiliated organization that serves the broader public."