Morrison & Foerster is seeking sanctions against employment firm Sanford Heisler Sharp in a jab at the lawyers who’ve sued several Big Law firms for gender discrimination.

The San Francisco-based firm accuses Sanford Heisler of filing frivolous claims in Jane Doe No. 4’s lawsuit. The petition states the plaintiff sued despite knowing that her separation agreement released Morrison & Foerster from all claims.

“Morrison does not bring a motion for sanctions lightly, but sanctions are required under these extraordinary circumstances,” attorneys with Gibson, Dunn & Crutcher representing Morrison & Foerster said in the April 8 filing.

The plaintiff is one of six ex-Morrison & Foerster attorneys who sued the firm in January claiming they were discriminated against after taking maternity leave.

Morrison & Foerster representatives April 9 referred to this week’s filing for the firm’s position.

Deborah Marcuse, managing partner for Sanford Heisler’s Baltimore office, who represents plaintiffs along with chairman and co-founder David Sanford, said the filing was a “baseless motion for sanctions, which is itself sanctionable conduct by MoFo.”

“It is regrettable that MoFo made the choice to terminate Jane Doe 4 when she was eight months pregnant, without prior notice. It is reprehensible that the Firm then demanded that Jane Doe 4 sign away her legal rights or give up the five months of paid maternity leave that she was counting on. MoFo’s conduct toward Jane Doe 4 constituted duress and undue influence warranting rescission of the agreement she signed,” Marcuse said in an April 9 statement.

Sanford Heisler also is litigating gender bias claims against Jones Dayand Ogletree, Deakins, Nash, Smoak & Stewart. It’s settled claims against Proskauer Rose, Chadbourne & Parke (now Norton Rose Fulbright), and the now-defunct firm Sedgwick.

Jane Doe 4 joined an existing putative class-action lawsuit against MoFo despite knowing that her separation agreement released MoFo from all claims, the petition claims.

“Specifically, her admissions that she (1) is an attorney, (2) consulted legal counsel before signing the Release, (3) obtained a higher severance payout as a result of her negotiations, and (4) acknowledged the legally recognized reasonable alternatives available to her, separately and together disprove her claims of undue influence and economic duress. As such, Jane Doe 4’s claims are knowingly baseless,” the motion said.

Morrison & Foerster is asking for dismissal with prejudice and attorneys’ fees. A May 16 hearing is scheduled before Magistrate Judge Jacqueline Scott Corley, U.S. District Court for the Northern District of California, in San Francisco.

The case is Doe v. Morrison & Foerster LLP, N.D. Cal., No. 3:18-cv-02542, sanctions motion 4/8/19.