From Tresco, Inc. v. Continental Cas. Co., 2010 U.S. Dist. LEXIS 71294 (D.N.M. July 2, 2010):

The Tenth Circuit***has not stated what is necessary to satisfy the requirement that all defendants "join in the removal petition." ***

The United States Courts of Appeals for the Fifth, Seventh, and Eighth Circuits, and some district courts, have held that each co-defendant must either sign the removal petition or submit a timely notice of consent in writing. ***

[Footnote 4] It is unclear how the courts that require the non-removing defendant to sign the notice of removal or file a separate written consent and joinder create this requirement. Clearly these courts do not find the requirement — or exception — in the removal statutes. And, if the requirement is not in the statutes, the courts' ability to create these rules — and exceptions to its rules — is questionable. While the procedures these courts require may be good policy, Congress has already set the policy in the plain language of the removal statutes and federal courts should hear these cases if they are removed. A federal court should not decline to hear a case that complies with the plain language of the statutes because of some court-made rule.

The United States Courts of Appeals for the Sixth and Ninth Circuits require only that at least one attorney of record sign the notice and certify that the remaining defendants consent to removal. ***

The Sixth Circuit also noted that rule 11 of the Federal Rules of Civil Procedure bound the attorney when she represented to the district court that another defendant *** consented to the removal. ***

Thus, the issue is whether one defense attorney can represent, under rule 11, that another defendant that the attorney does not represent consents to the transfer. Specifically, the issue is whether CNA can express its consent to removal only by either signing the notice of removal or by filing a separate document stating its consent or joinder, or if National Union's representation is sufficient.

That separate counsel represent CNA and National Union should not mean that CNA must file an independent notice of consent. The "rule of unanimity," which the Supreme Court announced in Chicago. Rock Island. & Pacific Railway Co. v. Martin, 178 U.S. 245,248 (1900), as an interpretation of a predecessor removal statute, says only that "all the defendants must join in the application" for removal. ***

Nothing in rule 11 prohibits counsel for one defendant from making representations on behalf of another defendant, or that defendant's counsel. See Harper v. AutoAlliance Int'l. Inc., 392 F.3d at 201-02 ("Nothing in Rule 11, however, required Kelly or his attorney to submit a pleading, written motion, or other paper directly expressing that concurrence or prohibited counsel for the other defendants from making such a representation on Kelly's behalf."); Proctor v. Vishay Intertechnology Inc., 584 F.3d at 1225 (reasoning that the possibility of rule 11 sanctions for making false averments mitigate the concern that one defendant might falsely state the other defendants' consent); Roybal v. City of Albuquerque, 2008 U.S. Dist. LEXIS 108749, at *21 ("Federal courts often rely on the representations of counsel about other parties.").

While not requiring each Defendant to either sign the removal petition or independently submit a timely notice of consent in writing may be contrary to the weight of authority on this subject, it does not run counter to the principles that: (i) removal statutes be strictly construed, with all doubts being resolved against removal, or with the requirements for notice of removal; (ii) any necessary joinder, or consent thereto, be timely filed within thirty days after service; and (iii) that the joinder or consent be strictly construed. The statute is not ambiguous; it is silent. It neither requires nor precludes the rule that Tresco requests. Hence, there is no doubt about what the statute requires. Strictly construing the plain language of the removal statute, and in the face of no Tenth Circuit law to the contrary, the Court concludes that the filing of a notice of removal can be effective without individual consent documents on behalf of each Defendant. Strict construction and resolving doubts against removal does not mean the courts should be hostile to the Congressionally created right to removal, creating procedural hurdles that Congress did not create and that provide pitfalls for all but the most experienced federal court litigants.