No. 97-1127.United States Court of Appeals, First Circuit.Heard October 8, 1997.
Decided February 5, 1998.
Charles Rothfeld, with whom Andrew L. Frey, Kenneth S. Geller, Mayer, Brown Platt, George A. Berman, Joseph S. Berman, Posternak, Blankstein Lund, Eric M. Rubin, Walter E. Diercks and Rubin, Winston, Diercks, Harris Cooke were on brief for appellant.
Peter L. Koff, with whom McGowan, Engel, Tucker, Garrett
Schultz, P.A., Arthur J. Goldberg and City of Cambridge Law Department were on brief for appellees.
Appeal from the United States District Court for the District of Massachusetts, [Hon. Edward F. Harrington, U.S. District Judge].
Before Boudin, Circuit Judge, Godbold and Cyr, Senior Circuit Judges.
CYR, Senior Circuit Judge.
 In an earlier opinion we held that the City of Cambridge had violated the First Amendment rights of Ackerley Communications of Massachusetts, Inc., by requiring it to remove various signs which failed to conform with a recently enacted zoning provision aimed at controlling the proliferation of aesthetically offensive signage. Ackerley Communications of Mass., Inc. v. City of Cambridge, 88 F.3d 33 (1st Cir. 1996) (“Ackerley I”). Ackerley now appeals from the judgement entered following our remand, claiming that the district court erred by refusing to void the offending zoning provision in its entirety. We vacate the district court judgement and remand with directions to enter judgement for Ackerley.
 I. BACKGROUND
 Ackerley owns forty-six large advertising signs or billboards, located throughout Cambridge, which carry “off-site” messages, by which we mean signs whose content relates to no commercial or noncommercial activity occurring at the premises where the sign is located. The City amended its ordinance in
1991 to require removal of all signs meeting certain objective criteria relating to dimension and location. See Cambridge, Mass., Ordinance 1123, § 7.18.1 (June 10, 1991).
 Under the amended criteria, all forty-six Ackerley signs carrying off-site messages were to be removed, since the ordinance contained no “grandfather” provision. The relevant legal environment is further complicated by the Massachusetts Zoning Enabling Act (“MZEA”), however, which prohibits any municipal zoning ordinance provision purporting to regulate existing on-site signage; that is, any sign carrying a message relating to a commercial or noncommercial activity occurring at the premises where the sign is located. See Mass. Gen. Laws Ann. ch. 40A, § 6 (1995).
 The City Council which enacted section 7.18.1 understood from the start that its effort to curb visual blight would be thwarted, at least in part, by the MZEA. Be that as it might, the City Council considered off-site signs, such as Ackerley’s, the greater aesthetic intrusion, see Ordinance § 7.11.1(F), in the sense that on-site signs at least serve a significant practical purpose by assisting consumers to locate a particular business establishment or product (“Joe’s Hardware”), see id. § 7.11.1(G). Accordingly, and since as a general matter the First Amendment does not prefer commercial speech over noncommercial (e.g., political) speech, the Ordinance included a “substitution” provision permitting the owner of a “grandfathered” on-site sign to substitute a noncommercial message for the commercial message previously displayed by its on-site sign (e.g., “Smith for Mayor” replaces “Joe’s Hardware”). See id. § 7.17. Finally, it included a “severability” clause saving all “parts” of the Ordinance not specifically held invalid. See id. § 7.30.
 Until the Ordinance was amended, most off-site signs owned by Ackerley carried commercial messages, such as advertisements and promotions concerning “for-profit” business ventures. Following its amendment, however, Ackerley’s signs have carried only noncommercial messages, such as election advertisements and public service announcements. Ultimately, since the MZEA “grandfather” provision does not cover existing off-site signs, the City directed Ackerley to remove all its signs based on their nonconforming physical characteristics, see Ordinance § 7.18.1.
 Ackerley responded by filing the present action in federal district court, seeking a judicial declaration that the Ordinance — on its face and as applied — infringed its First Amendment right to free speech. At the same time, Ackerley demanded injunctive relief from the City order directing it to dismantle its signs.
 On appeal we vacated the provisional district court ruling declaring Ordinance § 7.18.1 constitutional. Ackerley I, 88 F.3d at 40. First, we held that the Ordinance and the MZEA, operating in tandem, distinguished between two types of noncommercial speech — on-site and off-site — (i) by permitting nonprofit institutions to display on-site, noncommercial messages on nonconforming signs located on their own premises, and (ii) by allowing on-site sign owners to convert from commercial to noncommercial messages, while denying off-site sign owners either option. We noted that noncommercial speech — for example, political discourse — is accorded the highest level of First Amendment protection, yet the distinction adopted by the Ordinance — though predicated on no aesthetic difference in sign appearance (e.g., size) — plainly imposed unconstitutional restrictions upon the off-site noncommercial speech of the sign owner, by countenancing only those political messages espoused by the owner or occupant of the site where the sign is located, while excluding other political views, such as those held by non-landowners. Thus, we concluded, even though the City might ban all noncommercial messages from aesthetically intrusive signs, it cannot prefer one particular category of political speaker over another. Id. at 37-38.
 Furthermore, because the Ordinance and the MZEA, in tandem, either allowed or denied “grandfathering” protection based on
whether the sign carried an on-site or an off-site message on the date the Ordinance was enacted, we concluded that the City had chilled present speech impermissibly by relying on message content to reward on-site speakers for their past speech, while penalizing off-site speakers for their past speech. Id. at 38-39 (citing Ackerley Communications of Mass., Inc. v. City of Somerville, 878 F.2d 513, 519 (1st Cir. 1989)).
 In a separate discussion captioned “Remedial Option,” we went on to note that the City could not correct these unconstitutional effects unilaterally simply by eliminating the “grandfathering” distinction between on-site and off-site signs. See id. at 39-40. Instead, since it was the Commonwealth, through the MZEA, rather than the City through Ordinance § 7.18.1, which established the distinction between on-site and off-site signs, we stated that “[r]elief . . . is beyond the scope of this court’s power in this case[,]” id. at 39, since amendments to the MZEA “must be left to the workings of the political process.” Id. Accordingly, we concluded:
 The Cambridge ordinance contains a severability provision stating that, in the event some portion of it is declared invalid, it is the City’s intent that the remainder of the ordinance continue in full force and effect. We do not in this decision rule unlawful any particular section of the ordinance. Rather, because the constitutional problem stems from the interplay of the ordinance and the state provision, we hold only that Cambridge may not require removal of signs displaying noncommercial messages based on their exclusion from exemption under the state provision. Reversed and Remanded.
 Id. at 40.
 On remand, Ackerley requested a judicial declaration determining section 7.18.1 invalid in its entirety, which would mean that the City could not order the removal of any off-site sign, whether it carried a noncommercial message, as did Ackerley’s, or a commercial message. The City responded that Ackerley I conclusively ruled out any such wholesale rescission of Ordinance § 7.18.1. See id. (“We do not in this decision rule unlawful any particular section of the ordinance.”). The district court ultimately granted Ackerley declaratory relief “consistent with the decision [in Ackerley I]” and enjoined the City from requiring Ackerley to remove signs displaying noncommercial messages.
 II. DISCUSSION
 A. Law of the Case
 First, the City contends that the district court was powerless to declare section 7.18.1 invalid in its entirety on remand since Ackerley I expressly stated that we were not ruling “unlawful any particular section of the ordinance.” Ackerley I, 88 F.3d at 40. In other words, the City proposes to construe the quoted statement from Ackerley I as a binding pronouncement — the “law of the case” — that the unconstitutional effects of the MZEA “grandfathering” provision cannot be redressed through the judicial process, and, therefore, that the only relief available to Ackerley in the present litigation would be an order enjoining any application of section 7.18.1 to its noncommercial signs.
 We begin our analysis with a review of the unusual procedural posture in Ackerley I. The Ackerley complaint sought a judicial declaration that section 7.18.1, on its face and as applied, contravened the First Amendment, as well as the Fifth Amendment “takings” clause. Ackerley requested preliminary injunctive relief only in relation to its First Amendment claim. The district court thereafter denied preliminary injunctive relief, however, based on its determination that Ackerley had shown no “likelihood of success” on its First Amendment claim.
 As both parties acknowledged that no factfinding would be required to resolve the purely legal issues controlling their First Amendment dispute, at their express request we decided to bypass the provisional likelihood-of-success inquiry normally undertaken in interlocutory appeals from orders denying preliminary injunctive relief, and instead to resolve those issues finally. See Ackerley I, 88 F.3d at 35. Accordingly, and since neither party had sought a final determination as to all other issues which would have had to be decided before final judgement could be
entered, nor even briefed the question regarding what remedies might be available to Ackerley once it had been determined that the City had violated the First Amendment, we framed our inquiry narrowly: “The issue we must decide is whether Cambridge may enforce its sign ordinance to require Ackerley to remove its billboards.” Id. at 36 n. 6 (emphasis added). We responded in the negative.
 Although we found neither the MZEA nor the Ordinance to be unconstitutional in isolation, we held that their operation in tandem (i) violated the First Amendment by favoring on-site noncommercial speech over off-site noncommercial speech and (ii) penalized off-site speakers based on the content of their past speech. Id. at 37-39.
 Importantly, our Section II.D discussion in Ackerley I is captioned “Remedial Option,” not “Remedial Options.” Id. at 39. Moreover, its context makes clear that the Remedial Option discussion did not purport to treat with all judicial “remedies” available upon entry of final judgment, but with the more pragmatic and immediate concern as to how the First Amendment infirmity might be avoided, either unilaterally by the City or by “construct[ing] a justifiable, content-neutral grandfathering provision” in cooperation with the Commonwealth. Id. at 39-40. Finally, we went on to point out the awkward legal position in which the City Council had been placed, in that though it unquestionably possessed a legitimate interest in curbing unsightly signage, the Commonwealth of Massachusetts alone had the power to provide a unilateral legislative remedy for the First Amendment infirmity by eliminating the discrepant “grandfathering” treatment accorded on-site and off-site signs. Thus, nothing we said in Section II.D remotely suggested that recourse to the legislative process was the only avenue open to Ackerley.
 We repair once again to Ackerley I, where we prominently noted that the Ordinance contained a severability clause. The very next sentence stated: “We do not in this decision rule unlawful any particular section of the ordinance.” Were the quoted sentence to mean, as the City implicitly insists, that no Ordinance provision could be determined invalid on remand, our express reference to the severability clause — in the immediately preceding sentence — would be rendered meaningless.
 Instead, the contextual focus in the quoted sentence from Ackerley I was upon the word “particular,” whose inclusion was a clear acknowledgement that the forthcoming factfinding inquiry on remand could lead the district court to strike one or more portions of the Ordinance, but not all. As severability disputes usually turn on fact-intensive inquiries best left to the trial court in the first instance, see infra Section II.B, and no factfinding
had occurred at the preliminary injunction stage in Ackerley I, we accordingly reemphasized the limited nature of our holding: “we hold only that Cambridge may not require removal of signs displaying noncommercial messages based on their exclusion from exemption under the state provision.” (Emphasis added.) Thus, Ackerley I made no pronouncement on the law of the case with respect to the severability issue.
 B. Severability
 As the MZEA grandfathering provision was not amended in response to Ackerley I, the constitutional infirmity persists. Therefore, permanent injunctive relief may not be granted Ackerley without first determining whether any, and if so which, portion(s) of the Ordinance may be unlawful. See, e.g., National Adver. Co. v. Town of Babylon, 900 F.2d 551, 554 (2d Cir. 1990) (de facto effect of such a targeted injunction is “to sever the unconstitutional portions of the ordinances and to leave the remainder intact”). Since the district court did not address the severability issue on remand, the case must be returned for further proceedings, including any essential factfinding, unless we can make the severability determination now, with confidence, as a matter of law.
 The severability vel non of a state statute or municipal ordinance is controlled by state law. See Leavitt v. Jane L., 116 S.Ct. 2068, 2069 (1997); Exxon Corp. v. Hunt, 475 U.S. 355, 376
(1986). “`Where a statutory provision is unconstitutional, if it is in its nature separable from the other parts of the statute, so that they may well stand independently of it, and if there is no such connection between the valid and the invalid parts that the [legislative body] would not be expected to enact the valid part without the other, the statute will be held good, except in that part which is in conflict with the Constitution.'” Mayor of Boston v. Treasurer Receiver Gen., 429 N.E.2d 691, 695 (Mass. 1981) (citation omitted). On the other hand, “[i]f the court is unable to know whether the Legislature would have enacted a particular bill without the unconstitutional provision, it will not sever the unconstitutional provision, but will strike the entire statute.” Id.
 At the very least, Ackerley is entitled to a judicial declaration invalidating section 7.18.1 to the extent it would require removal of nonconforming off-site signs carrying noncommercial messages. The severability issue thus devolves into an impressionistic inquiry into whether section 7.18.1 would have been enacted had the City Council known that it would require only the removal of nonconforming off-site signs carrying commercial messages. As we cannot divine with confidence what the City Council would have done, Mayor of Boston, 429 N.E.2d at 695, the case must be remanded to the district court with directions to enter a final judgement invalidating section 7.18.1 in its entirety. We explain.
 Severability clauses, though probative of legislative intent, are not conclusive. See, e.g., Reno v. ACLU, 117 S.Ct. 2329, 2351
n. 49 (1997) (“[A] severability clause is `an aid merely; not an inexorable command.'”) (citation omitted). Although Ordinance § 7.30, see supra p. 4, only applies to invalidated “parts” of the Ordinance, that term begs the question in the present context. Section 7.18.1 was neither drafted nor enacted in separate “parts” which discretely banned
commercial and noncommercial off-site signs, either of which might be stricken independently of the other. Neither section 7.18.1, nor any other “part” of the Ordinance, alludes in any way to a substantive distinction between commercial and noncommercial messages. Nor can such a substantive distinction be read into section 7.18.1, without in effect gratuitously supplementing its language with the phrase “except for offsite signs bearing noncommercial messages.” Therefore, as we cannot say with confidence that the City Council envisioned section 7.18.1 as anything but a unitary “part” of the Ordinance, the severability clause avails the City nothing.
 Furthermore, although at first blush it may appear that settled principles of federalism and separation of powers would counsel that the explicit severability presumption contained in Ordinance § 7.30 be given literal sway, there is more here than meets the eye. The severability principles controlling the present decision were intended principally to ensure that the courts, state and federal, not dissuade or preempt legislative bodies from debating and determining the appropriate public policy in the first instance, within constitutional limits. See, e.g., Reno, 117 S.Ct. at 2351 n. 49 (“`It would certainly be dangerous if the Legislature could set a net large enough to catch all possible offenders and leave it to the courts to step inside and say who could rightfully be detained and who should be set at large. This would, to some extent, substitute the judicial for the legislative department of the government.'”) (citation omitted). Thus, proper respect for the principles of federalism and separation of powers counsels against construing section 7.30 as a “cure all” for the severability ills in the present Ordinance.
 The City further contends that the Council enacted the Ordinance to eliminate nonconforming signs to the maximum extent allowed by law, and that severance would prevent Ackerley and other sign owners from converting their off-site sign messages to more lucrative commercial messages, thereby providing a strong financial disincentive to maintaining such signs in the future. Be that as it might, however, the suggested distinction also would entail significant administrative burdens and expense for the City, which would be required to police nonconforming off-site signs to determine whether they carried only the permitted “noncommercial” messages, articulate objective criteria for making the often blurry distinction between “commercial” and “noncommercial” speech, and provide sign owners with a forum in which to address their challenges to, and appeals from, any adverse City determination that a particular message was “commercial.” See Metromedia, Inc. v. City of San Diego, 649 P.2d 903, 908 (Cal. 1982) (rejecting “severability” claim on same ground).
 Moreover, nothing in the Ordinance indicates that the Council ever considered that the City would need to police, hear, or determine the commercial-noncommercial distinction in order to implement its chosen aesthetic objectives. Nor has the City pointed to any probative evidence of such legislative consideration which might be material on remand. Thus, although the blurriness of the commercial-noncommercial distinction itself may not render the amended ordinance unconstitutional, courts confronted with severability questions clouded by serious uncertainties regarding whether the appropriate legislative body ever considered the effect of a severability provision in the relevant context, ought not be anxious to arrogate the legislative prerogative inherent in determining the preferred or more efficient means of pursuing the particular goals chosen by the responsible legislative body.
 The City Council may decide to adopt less onerous initiatives than the presumably burdensome and expensive administrative procedures which would be required were we not to invalidate section 7.18.1 in toto. For example, it might determine that the municipality’s interests would be better served by attempting to persuade the state legislature to approve a content-neutral grandfathering provision based exclusively on the physical characteristics of existing signs, rather than their content. See Ackerley I, 88 F.3d at 39-40. Thus, we think such important policy decisions are for the Council in the first instance.
 III. CONCLUSION
 As the City points to no factual circumstance which, if demonstrated on remand, would affect our severability determination, we can discern no substantial benefit from a further remand. Accordingly, the case is remanded to the district court for entry of final judgment declaring section 7.18.1 invalid in toto, and enjoining the City from requiring Ackerley to remove signs pursuant to section 7.18.1 as presently written. So ordered.
An onsite sign carries a message that bears some relationship to the activities conducted on the premises where the sign is located. For example, an onsite sign may simply identify a business or agency (“Joe’s Hardware” or “YMCA”), or it may advertise a product or service available at that location (“Budweiser Beer” at Parise’s Cafe or child care at the Lutheran Church). Depending upon the business or agency, the message on the sign may be deemed either commercial or noncommercial. An offsite sign — the category into which most billboards fit — carries a message unrelated to its particular location. These signs also may display either commercial or noncommercial messages. For example, an offsite sign may advertise “Great Gifts at Kappy’s Liquors,” with Kappy’s Liquors being located at some distance from the sign, or it may say “No one should be left out in the cold. Write: Citizens Energy Corp.” Thus, the onsite/offsite distinction is not a distinction between signs attached to buildings and free standing signs. An offsite sign may be located on a building rooftop, but because the product, good, or service it advertises is not available at the sign’s location, it is classified as offsite. For example, if a sign advertising the products available at Joe’s Hardware is located atop the Parise Cafe building, Joe’s sign is offsite.
Ackerley Communications of Mass., Inc. v. City of Somerville, 878 F.2d 513, 513 n. 1 (1st Cir. 1989) (Coffin, J.).
The City Council must take Commonwealth law as it finds it; the MZEA supersedes § 7.18.1; therefore, either the MZEA must be modified through “the workings of the political process,” or § 7.18.1 must be declared unconstitutional and void, at least in part.
Unless at least part of § 7.18.1 was rendered invalid by the MZEA, there can have been no legal basis whatever for the district court order enjoining the City from directing Ackerley to remove its noncommercial signs. Finally, if the district court injunction, implicitly and necessarily, was predicated on a partial invalidation of § 7.18.1, then the district court must necessarily have resolved the closely related severability question as well.
(1993) (remanding for severability determination); Planned Parenthood of S.E. Pa. v. Casey, 505 U.S. 833, 901 (1992) (same); FW/PBS, Inc. v. City of Dallas, 493 U.S. 215, 230 (1990) (same); City of Lakewood v. Plain Dealer Pub. Co., 486 U.S. 750, 772
(1st Cir. 1995) (noting generally that First Circuit panels are bound by prior panel decisions directly on point).