IN THE SUPREME COURT OF 

CALIFORNIA

MONTROSE CHEMICAL CORPORATION

OF CALIFORNIA,

Petitioner,

v.

THE SUPERIOR COURT OF LOS ANGELES COUNTY,

Respondent;

CANADIAN UNIVERSAL INSURANCE

COMPANY, INC., et al.,

Real Parties in Interest.

S244737

Second Appellate District, Division Three

B272387

Los Angeles County Superior Court

BC005158
April 6, 2020

Justice Kruger authored the opinion of the Court, in which 

Chief Justice Cantil-Sakauye and Justices Liu, Cuéllar, 

Groban, Elia,* and Brown** concurred.

 

* Associate Justice of the Court of Appeal, Sixth Appellate 

District, assigned by the Chief Justice pursuant to article VI, 

section 6 of the California Constitution.

** Associate Justice of the Court of Appeal, First Appellate 

District, Division Four, assigned by the Chief Justice pursuant 

to article VI, section 6 of the California Constitution.
1

MONTROSE CHEMICAL CORPORATION OF CALIFORNIA

v. SUPERIOR COURT

S244737

Opinion of the Court by Kruger, J.

Montrose Chemical Corporation (Montrose) was sued for 

causing continuous environmental damage in the Los Angeles 

area between 1947 and 1982 and subsequently entered into 

partial consent decrees to resolve various claims. Montrose now 

seeks to tap its liability insurance to cover amounts it owes in 

connection with those claims. For each policy year from 1961 to 

1985, Montrose had secured primary insurance and multiple 

layers of excess insurance. This case concerns the sequence in 

which Montrose may access the excess insurance policies

covering this period. 

Montrose argues it is entitled to coverage under any 

relevant policy once it has exhausted directly underlying excess 

policies for the same policy period. The insurers, by contrast, 

argue that Montrose may call on an excess policy only after it 

has exhausted every lower level excess policy covering the 

relevant years. Reading the insurance policy language in light 

of background principles of insurance law, and considering the 

reasonable expectations of the parties, we agree with Montrose: 

It is entitled to access otherwise available coverage under any 

excess policy once it has exhausted directly underlying excess 

policies for the same policy period. An insurer called on to 

provide indemnification may, however, seek reimbursement

from other insurers that would have been liable to provide 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

2

coverage under excess policies issued for any period in which the 

injury occurred.

I.

We have previously recounted the basic facts underlying 

this dispute. (See Montrose Chemical Corp. v. Superior Court

(1993) 6 Cal.4th 287, 292–294.) To summarize, Montrose 

manufactured the insecticide dichloro-diphenyl-trichloroethane 

(DDT) at its facility in Torrance from 1947 to 1982. In 1990, the 

United States and the State of California sued Montrose for 

environmental contamination allegedly caused by Montrose’s 

operation of this facility. Montrose entered into partial consent 

decrees in which it agreed to pay for environmental cleanup. To 

meet its obligations, Montrose has now expended millions of 

dollars—Montrose represents the total is more than $100 

million—and asserts that its anticipated future liability could 

approach or exceed this amount.

Montrose purchased primary and excess comprehensive 

general liability insurance to cover its operations at the 

Torrance facility from defendant insurers between 1961 and

1985. Primary insurance refers to the first layer of coverage, 

whereby “liability attaches immediately upon the happening of 

the occurrence that gives rise to liability.” (Olympic Ins. Co. v. 

Employers Surplus Lines Ins. Co. (1981) 126 Cal.App.3d 593, 

597.) Excess insurance, by contrast, “refers to indemnity 

coverage that attaches upon the exhaustion of underlying 

insurance coverage for a claim.” (County of San Diego v. Ace 

Property & Casualty Ins. Co. (2005) 37 Cal.4th 406, 416, fn. 4.) 

An excess insurer’s coverage obligation begins once a certain 

level of loss or liability is reached; that level is generally referred 

to as the “attachment point” of the excess policy. (Rest., Liability 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

3

Insurance, § 39, com. d, p. 338.) Here, 40 insurers collectively 

issued more than 115 excess policies during the 1961 to 1985

period, which collectively provide coverage sufficient to 

indemnify Montrose’s anticipated total liability. 

Montrose and the insurers, which are the real parties in 

interest here,1 agree for purposes of this dispute that Montrose’s 

 

1 The real party insurers are: Continental Casualty 

Company and Columbia Casualty Company, joined by AIU 

Insurance Company; Allstate Insurance Company (solely as 

successor in interest to Northbrook Excess and Surplus 

Insurance Company); American Centennial Insurance 

Company; American Home Assurance Company; Federal 

Insurance Company; Employers Insurance of Wausau; Everest 

Reinsurance Company (as successor in interest to Prudential 

Reinsurance Company); Fireman’s Fund Insurance Company; 

General Reinsurance Corporation; Granite State Insurance 

Company; Lamorak Insurance Company (formerly known as 

OneBeacon America Insurance Company, as successor in

interest to Employers Commercial Union Insurance Company of 

America, The Employers Liability Assurance Corporation, Ltd., 

and Employers Surplus Lines Insurance Company); Employers 

Mutual Casualty Company; Landmark Insurance Company; 

Lexington Insurance Company; Mt. McKinley Insurance 

Company (as successor in interest to Gibraltar Casualty 

Company); Munich Reinsurance America, Inc. (formerly known 

as American Re-Insurance Company); National Surety 

Corporation; National Union Fire Insurance Company of 

Pittsburgh, PA; New Hampshire Insurance Company; North 

Star Reinsurance Corporation; Providence Washington 

Insurance Company (as successor by way of merger to Seaton 

Insurance Company, formerly known as Unigard Security 

Insurance Company, formerly known as Unigard Mutual 

Insurance Company); Transport Insurance Company (as 

successor in interest to Transport Indemnity Company); 

Westport Insurance Corporation (formerly known as Puritan 

Insurance Company, formerly known as The Manhattan Fire 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

4

primary coverage has been exhausted. Further, the parties 

have stipulated to the relevant language found in the excess 

policies.2 Specifically, each policy provides that Montrose must 

exhaust the limits of its underlying insurance coverage before 

there will be coverage under the policy. The policies describe 

the applicable underlying coverage in four main ways:

1. Some policies contain a schedule of underlying 

insurance listing all of the underlying policies in the same policy 

period by insurer name, policy number, and dollar amount.

2. Some policies reference a specific dollar amount of 

underlying insurance in the same policy period and a schedule 

of underlying insurance on file with the insurer.

3. Some policies reference a specific dollar amount of 

underlying insurance in the same policy period and identify one 

or more of the underlying insurers.

4. Some policies reference a specific dollar amount of 

underlying insurance that corresponds with the combined limits 

of the underlying policies in that policy period.

 

and Marine Insurance Company); Zurich International 

(Bermuda), Ltd.

Insurers Travelers Casualty and Surety Company 

(formerly known as Aetna Casualty and Surety Company) and 

The Travelers Indemnity Company opposed Montrose on 

independent grounds and filed a separate answering brief.

2 The record does not contain complete copies of every policy 

between Montrose and the insurers. Instead, the parties have 

identified the terms of these policies that they believe are 

sufficient to resolve this dispute. The parties agree the various 

policies use different language that all communicates the same 

exhaustion requirement in different ways. 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

5

In a variety of ways, the excess policies also provide that 

“other insurance” must be exhausted before the excess policy 

can be accessed. Relevant examples include the following:

• Some policies provide that they will “indemnify the 

insured for the amount of loss which is in excess of the 

applicable limits of liability of the [scheduled] underlying 

insurance,” and then define “loss” as “the sums paid as 

damages in settlement of a claim or in satisfaction of a 

judgment for which the insured is legally liable, after 

making deductions for all recoveries, salvages and other 

insurances (whether recoverable or not) other than the 

underlying insurance and excess insurance purchased 

specifically to be in excess of this policy.” (Italics added.)

• Some policies state that the insurer is liable for “the 

ultimate net loss in excess of the retained limit” and define 

“retained limit” to mean, among other things, the “total of 

the applicable limits of the underlying policies listed in [a 

schedule] [and] the applicable limits of any other 

underlying insurance collectible by the insured.” (Italics 

added.)

• Under a “Loss Payable” provision, one policy provides it

will pay “any ultimate net loss,” which is separately 

defined as “the sums paid in settlement of losses for which 

the Insured is liable after making deductions for all 

recoveries, salvages and other insurance (other than 

recoveries under the underlying insurance, policies of coinsurance, or policies specifically in excess hereof).” (Italics 

added.)

• Under a “Limits” provision, some policies provide that “the 

insurance afforded under this policy shall apply only after 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

6

all underlying insurance has been exhausted.” (Italics 

added.)

• One policy states that “[i]f other valid and collectible 

insurance with any other insurer is available to the 

Insured covering a loss also covered by this policy, other 

than insurance that is in excess of the insurance afforded 

by this policy, the insurance afforded by this policy shall 

be in excess of and shall not contribute with such other 

insurance.” (Italics added.)

Montrose and the insurers disagree whether these 

clauses—which we will collectively call “other insurance” 

clauses—require Montrose to exhaust other insurance coverage 

from other policy periods. This dispute dates to 1990, when 

Montrose first sued its insurers to resolve various coverage 

disputes, but the relevant filing for our purposes occurred in 

2015, when Montrose’s fifth amended complaint asserted a new 

cause of action seeking the following declaration:

“a. In order to seek indemnification under the Defendant 

Insurers’ excess policies, Montrose need only establish that its 

liabilities are sufficient to exhaust the underlying policy(ies) 

in the same policy period, and is not required to establish that 

all policies insuring Montrose in every policy period (including 

policies issued to cover different time periods both before and 

after the policy period insured by the targeted policy) with limits 

of liability less than the attachment point of the targeted policy, 

have been exhausted; and

“b. Montrose may select the manner in which [to] allocate 

its liabilities across the policy(ies) covering such losses.”
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

7

The rule Montrose proposes in its amended complaint is a 

rule of “vertical exhaustion” or “elective stacking,” whereby it 

may access any excess policy once it has exhausted other policies 

with lower attachment points in the same policy period. The

insurers, in contrast, each of which has issued an excess policy 

to Montrose in one of the triggered policy years, argue for a rule 

of “horizontal exhaustion,” whereby Montrose may access an 

excess policy only after it has exhausted other policies with 

lower attachment points from every policy period in which the 

environmental damage resulting in liability occurred. The 

parties filed cross-motions for summary adjudication of this 

issue.3

The trial court denied Montrose’s motion and granted the 

insurers’ motion, holding that the excess policies required 

horizontal exhaustion in the context of this multiyear injury. 

The court concluded there is a “ ‘well-established rule that 

horizontal exhaustion should apply in the absence of policy 

language specifically describing and limiting the underlying 

insurance.’ ” Montrose filed a petition for a writ of mandate, 

 

3 One set of insurers, Travelers Casualty and Surety 

Company and The Travelers Indemnity Company (collectively, 

Travelers), opposed Montrose’s motion for summary 

adjudication for two independent reasons. First, Travelers 

argued that Montrose’s requested declaration would entitle 

Montrose to indemnification without actually exhausting the 

relevant underlying insurance, as required by the terms of the 

Travelers policies. Travelers further argued that California law 

did not apply to their policies. Because the Court of Appeal 

concluded for other reasons that Montrose was not entitled to 

summary adjudication, it did not address the issues raised by 

Travelers. We did not grant review of either question, as 

discussed at part II.D., post.
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

8

which the Court of Appeal summarily denied. We granted 

Montrose’s petition for review and transferred the case to the 

Court of Appeal with instructions to issue an order to show 

cause why the relief Montrose sought should not be granted.

The Court of Appeal affirmed the trial court’s denial of 

Montrose’s motion for summary adjudication and affirmed in 

part the trial court’s grant of the insurers’ parallel motion. 

(Montrose Chemical Corp. v. Superior Court (2017) 14 

Cal.App.5th 1306, 1321, 1338 (Montrose II).) The court 

concluded that the plain language of many of the excess policies 

purchased by Montrose provide that they “attach not upon 

exhaustion of lower layer policies within the same policy period, 

but rather upon exhaustion of all available insurance.” (Id. at 

p. 1327.)

Shortly after the Court of Appeal published its opinion in 

this case, another Court of Appeal disagreed with its reasoning 

in State of California v. Continental Ins. Co. (2017) 15 

Cal.App.5th 1017. The court in that case determined that 

vertical exhaustion was appropriate given the relevant policy 

language and our case law. (Id. at pp. 1031–1037.)

We granted review in this case to determine whether 

vertical exhaustion or horizontal exhaustion is required when 

continuous injury occurs over the course of multiple policy 

periods for which an insured purchased multiple layers of excess 

insurance. Reading the relevant policy language in light of 

background principles of insurance law and considering the 

parties’ reasonable expectations, we conclude that a rule of 

vertical exhaustion is appropriate. Under that rule, the insured 

has access to any excess policy once it has exhausted other 

directly underlying excess policies with lower attachment 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

9

points, but an insurer called upon to indemnify the insured’s loss 

may seek reimbursement from other insurers that issued 

policies covering relevant policy periods.4

II.

A.

We begin our analysis with a few background insurance 

law principles specific to the continuous or “long-tail” injury at 

issue here, where damage occurs over multiple policy periods. 

(See State of California v. Continental Ins. Co. (2012) 55 Cal.4th 

186, 195–196 (Continental).) In a much earlier iteration of this 

case, we noted “the settled rule” is that “an insurer on the risk 

when continuous or progressively deteriorating damage or 

injury first manifests itself remains obligated to indemnify the 

insured for the entirety of the ensuing damage or injury,” up to 

the policy’s limit. (Montrose Chemical Corp. v. Admiral Ins. Co.

(1995) 10 Cal.4th 645, 686, italics added (Montrose I).) “There 

is no requirement that . . . the conditions giving rise to the 

damage or injury . . . themselves occur within the policy period 

in order for potential liability coverage to arise.” (Ibid.) 

Extending this logic to the continuous injury context, we held 

that “bodily injury and property damage which is continuous or 

progressively deteriorating throughout several policy periods is 

potentially covered by all policies in effect during those periods.” 

(Id. at p. 689.) This principle is also known as the “continuous 

injury trigger of coverage.” (Ibid.)

 

4 Because the question is not presented here, we do not 

decide when or whether an insured may access excess policies 

before all primary insurance covering all relevant policy periods 

has been exhausted.
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

10

In Aerojet-General Corp. v. Transport Indemnity Co.

(1997) 17 Cal.4th 38, 57 (Aerojet), we illustrated the principle 

with an example: If an insured company discharges a hazardous 

substance that causes property damage in the amount of 

$100,000 each year for a span of 30 years, a $1 million insurance 

policy that is purchased for the first year of that 30-year span 

would be required to pay the insured the full $1 million limit for 

indemnification. Even though the damage traceable to the 

policy year in which the insurance policy was in effect only 

amounted to $100,000, the insurer is liable for all damages. As 

we explained, the insurer’s obligation to pay is “triggered if 

specified harm is caused by an included occurrence, so long as 

at least some such harm results within the policy period.” (Id.

at p. 56, fn. omitted, citing Montrose I, supra, 10 Cal.4th at 

pp. 669–673.) “It extends to all specified harm caused by an 

included occurrence, even if some such harm results beyond the 

policy period.” (Aerojet, at pp. 56–57.) 

This “all sums” rule, as we described it in Aerojet, means

that “insurers [a]re responsible for defending the insured for all 

claims that involved the triggering damage” in a continuous 

injury case; “as long as the policyholder is insured at some point 

during the continuing damage period, the insurers’ indemnity 

obligations persist until the loss is complete, or terminates.” 

(Continental, supra, 55 Cal.4th at p. 197, citing Aerojet, supra, 

17 Cal.4th at p. 71; Continental, at p. 200 [under all sums 

allocation, insurers must “pay all sums for property damage 

attributable to the [polluted] site, up to their policy limits, if 

applicable, as long as some of the continuous property damage 

occurred while each policy was ‘on the loss’ ”].) We adopted this 

rule because, contrary to Aerojet’s stylized example, “[i]t is often 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

11

‘virtually impossible’ for an insured to prove what specific 

damage occurred during each of the multiple consecutive policy 

periods in a progressive property damage case.” (Id. at p. 196.) 

“If such evidence were required, an insured who had procured 

insurance coverage for each year during which a long-tail injury 

occurred likely would be unable to recover.” (Ibid.) The all sums 

approach, we explained, “best reflects the insurers’ indemnity 

obligations under the respective policies, the insured’s 

expectations, and the true character of the damages that flow 

from a long-tail injury.” (Id. at p. 200.)

Finally, recognizing that the limits of any one policy may 

be insufficient to cover the entire liability resulting from a 

continuous injury, we concluded in Continental that the insured 

may seek indemnification from every policy that covered a 

portion of the loss, up to the full limits of each policy. 

(Continental, supra, 55 Cal.4th at p. 200.) This “all-sums-withstacking indemnity principle,” we said, “properly incorporates 

the Montrose [I] continuous injury trigger of coverage rule and 

the Aerojet all sums rule, and ‘effectively stacks the insurance 

coverage from different policy periods to form one giant “uberpolicy” with a coverage limit equal to the sum of all purchased 

insurance policies.’ ” (Id. at p. 201.) “ ‘[T]his approach treats all 

the triggered insurance as though it were purchased in one 

policy period’ ” and recognizes “the uniquely progressive nature 

of long-tail injuries that cause progressive damage throughout 

multiple policy periods.” (Ibid.) Importantly, “the insured has 

immediate access to the insurance it purchased.” (Ibid.) The 

insurers can then sort out their proportional share through 

actions for equitable contribution or subrogation. (Id. at p. 200; 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

12

see Continental Cas. Co. v. Zurich Ins. Co. (1961) 57 Cal.2d 27, 

37.)5

Having adopted an all-sums-with-stacking approach to 

the coverage of long-tail injuries, we are now presented with a 

follow-on question: In what order may an insured access excess 

policies from different policy periods to cover liability arising 

from long-tail injuries? To illustrate the parties’ competing 

approaches, consider a hypothetical company that caused 

property damage over three years that resulted in $90 million of 

damage. Further imagine that in each of these three years, the 

company had purchased primary insurance with a $10 million 

limit and two layers of excess insurance, each providing an 

additional $10 million of coverage:

 

5

In a contribution action, an insurer that paid more than 

its share in the initial coverage action can seek reimbursement 

from other insurers that were obligated to indemnify or defend 

the same loss or claim. (Fireman’s Fund Ins. Co. v. Maryland 

Casualty Co. (1998) 65 Cal.App.4th 1279, 1293.) The doctrine of 

equitable subrogation allows an insurer to stand in the shoes of 

the insured and recover from third parties that are liable to the 

insured for a loss that the insurer both insured and paid. (Id. at 

pp. 1291–1292.) As a general matter, these types of actions 

allow insurers to apportion liability for losses among themselves 

after the insured has been indemnified.
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

13

Year 1 Year 2 Year 3

$50 million

$40 million

$30 million Policy 2A Policy 2B Policy 2C

$20 million Policy 1A Policy 1B Policy 1C

$10 million Primary 

Insurance

Primary 

Insurance

Primary 

Insurance

We are tasked with deciding between two proposed 

methods by which these six excess insurance policies might be 

stacked after the primary insurance has been exhausted to cover 

the $90 million liability in a way that “ ‘treats all the triggered 

insurance as though it were purchased in one policy period.’ ” 

(Continental, supra, 55 Cal.4th at p. 201.) Under the insurers’ 

proposed rule of horizontal exhaustion, the insured would have 

to exhaust all of its lower layer excess coverage across all 

relevant policy periods before accessing any of its higher layer 

coverage:
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

14

$90 million Policy 2C

$80 million Policy 2B

$70 million Policy 2A

$60 million Policy 1C

$50 million Policy 1B

$40 million Policy 1A

$30 million Primary 

Insurance

$20 million Primary 

Insurance

$10 million Primary 

Insurance

Under Montrose’s proposed rule of vertical exhaustion, in 

contrast, an insured would be permitted to access any higher

layer excess policy once it has exhausted the directly underlying 

excess policy covering the same period:
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

15

$90 million Policy 2C

$80 million Policy 1C

$70 million Policy 2B

$60 million Policy 1B

$50 million Policy 2A

$40 million Policy 1A

$30 million Primary 

Insurance

$20 million Primary 

Insurance

$10 million Primary 

Insurance

Which approach applies depends on the terms of the 

parties’ agreement. We therefore begin by looking, as we must, 

to the language of the insurance policies at issue. (Minkler v. 

Safeco Ins. Co. of America (2010) 49 Cal.4th 315, 321 (Minkler); 

AIU Ins. Co. v. Superior Court (1990) 51 Cal.3d 807, 822–823.)

B.

“The principles governing the interpretation of insurance 

policies in California are well settled. ‘Our goal in construing 

insurance contracts, as with contracts generally, is to give effect 

to the parties’ mutual intentions. [Citations.] “If contractual 

language is clear and explicit, it governs.” [Citations.] If the

terms are ambiguous [i.e., susceptible of more than one 

reasonable interpretation], we interpret them to protect “ ‘the 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

16

objectively reasonable expectations of the insured.’ ” ’ ” 

(Minkler, supra, 49 Cal.4th at p. 321.) If these rules do not 

resolve an ambiguity, we may then “ ‘resort to the rule that 

ambiguities are to be resolved against the insurer.’ ” (Ibid.)

The parties’ dispute centers on the meaning of the “other 

insurance” clauses in the excess insurance policies. These 

clauses provide, in a variety of ways, that each policy shall be 

excess to other insurance available to the insured, whether or 

not the other insurance is specifically listed in the policy’s 

schedule of underlying insurance. The insurers argue that these 

clauses call for a rule of horizonal exhaustion because they 

restrict indemnification from any excess policy until the insured 

has exhausted all other available insurance—which, in a case of 

long-tail injury, means every policy with a lower attachment 

point from every policy period triggered by the continuous 

injury.

Although the insurers’ interpretation is not an 

unreasonable one, it is not the only possible interpretation of the 

policy language.6 The “other insurance” clauses at issue clearly 

 

6 Nor, contrary to the insurers’ suggestion, has this 

interpretation already been adopted in California cases. The 

insurers invoke various cases interpreting “other insurance” 

clauses in other settings, but none addresses the question here: 

whether “other insurance” clauses require horizontal 

exhaustion of excess insurance policies in cases involving longtail injury. (See, e.g., Legacy Vulcan Corp. v. Superior Court 

(2010) 185 Cal.App.4th 677, 689–690 [addressing defense 

obligations of a policy providing both excess and “umbrella” 

defense coverage]; Peerless Cas. Co. v. Continental Cas. Co.

(1956) 144 Cal.App.2d 617, 625–626 [excess insurer not required 

to contribute when insurance settlement was prorated across 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

17

require exhaustion of underlying insurance, but none clearly or 

explicitly states that Montrose must exhaust insurance with 

lower attachment points purchased for different policy periods. 

Policies that disclaim coverage for amounts covered by “other 

underlying insurance,” or require exhaustion of “all underlying 

insurance,” for example, could fairly be read to refer only to 

other directly underlying insurance in the same policy period

that was not specifically identified in the schedule of underlying 

insurance, anticipating that the scheduled underlying 

insurance may later be replaced or supplemented with different 

policies. 

Other formulations require deductions for, in the words of 

one set of representative policies, all “other insurances (whether 

recoverable or not) other than the underlying insurance and 

excess insurance purchased specifically to be in excess of this 

policy.” (Italics added.) If this language were read to apply to 

insurance purchased for other policy periods, it could fairly be 

understood to require the exhaustion of every other insurance 

policy at every attachment point—not merely, as the insurers’ 

theory of horizontal exhaustion would have it, excess policies 

from other policy periods that contain lower attachment points. 

The insurers do not advance this expansive reading, however; 

they contend that the reference to “other insurance,” properly 

understood, means “other underlying insurance”—that is, only 

excess insurance with lower attachment points from all relevant 

policy periods. The insurers do not explain why the reference is 

not properly understood to mean “other directly underlying

 

two primary insurers and at least one primary policy remained 

unexhausted].)
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

18

insurance”—that is, a requirement that the insured exhaust 

only excess insurance with lower attachment points from the 

same policy period. This is one clue that the plain language of 

these clauses is not adequate to resolve the dispute in the 

insurers’ favor.

Consideration of the traditional use of “other insurance” 

clauses reinforces our doubts about the insurers’ interpretation. 

As we have previously explained, “ ‘[h]istorically, “other 

insurance” clauses were designed to prevent multiple recoveries 

when more than one policy provided coverage for a particular 

loss.’ ” (Dart Industries, Inc. v. Commercial Union Ins. Co.

(2002) 28 Cal.4th 1059, 1079 (Dart).) They have not generally 

been understood as dictating a particular exhaustion rule for 

policyholders seeking to access successive excess insurance 

policies in cases of long-tail injury.

In Dart, we considered the meaning of an “other 

insurance” clause in a different context. There, the policyholder

had acquired successive primary policies covering multiple 

decades and subsequently sought defense and indemnity from 

one of its primary insurers for a continuous injury during that 

time even though the policy provided by that insurer had been 

lost or destroyed. (Dart, supra, 28 Cal.4th at pp. 1064–1065.) 

The policyholder was able to prove the material terms of the 

policy, but the insurer argued that its contractual obligations 

may have been relieved or reduced by an “other insurance” 

clause in the lost policy, pointing to the other policies purchased 

for the period during which the injury occurred. (Id. at p. 1078.) 

We rejected this argument, explaining that reliance on an “other 

insurance” clause could not be used to “defeat the insurer’s 

obligations altogether.” (Id. at p. 1079.) In other words, the 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

19

insurer in Dart could not simply invoke the possibility of an 

“other insurance” clause to escape its coverage obligations. We 

reasoned, in a passage the parties have focused on here: 

“ ‘[A]pportionment among multiple insurers must be 

distinguished from apportionment between an insurer and its 

insured. When multiple policies are triggered on a single claim, 

the insurers’ liability is apportioned pursuant to the “other 

insurance” clauses of the policies [citation] or under the 

equitable doctrine of contribution [citations]. That 

apportionment, however, has no bearing upon the insurers’ 

obligations to the policyholder. . . . The insurers’ contractual 

obligation to the policyholder is to cover the full extent of the 

policyholder’s liability (up to the policy limits).’ ” (Id. at p. 1080, 

quoting Armstrong World Industries, Inc. v. Aetna Casualty & 

Surety Co. (1996) 45 Cal.App.4th 1, 105–106.) 

The parties dispute whether Dart meant to set out a 

categorical view of the meaning of “other insurance” clauses in 

cases of continuous injury and whether that view forecloses the 

insurers’ proposed interpretation of the “other insurance” 

clauses in the distinct context we confront here. Citing Dart, 

Montrose asserts that the “other insurance” clauses are relevant 

to contribution actions between insurers but not to coverage 

actions between insurers and policyholders. (See State of 

California v. Continental Ins. Co., supra, 15 Cal.App.5th at 

p. 1032.) We need not rely on any such categorical rule in this 

case, however; it is enough to observe that Dart undermines the 

insurers’ claim that the “other insurance” clauses clearly and 

explicitly call for a rule of horizontal exhaustion. 

In rejecting the insurer’s claim in Dart, we emphasized 

that “other insurance” clauses have not traditionally been used 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

20

to address questions concerning the obligation of successive 

insurers to indemnify policyholders for a continuously 

manifesting injury (a question which, as Dart reminds us, “is a 

separate issue from the obligations of the insurers to each other”

(Dart, supra, 28 Cal.4th at p. 1080)). (Id. at p. 1078, fn. 6.) 

Elaborating on the same point, the Restatement explains that 

“other insurance” clauses have generally been used to address 

“[a]llocation questions with respect to overlapping concurrent 

policies.” (Rest., Liability Insurance, supra, § 40, com. c, p. 345, 

italics added.) Consistent with this understanding, most courts 

to address the issue have found that “other insurance” clauses 

are not aimed at governing the proper allocation of liability 

among successive insurers in cases of long-tail injury or the 

appropriate sequence in which a policyholder may access its 

insurance across several policy periods. (Id., § 41, com. j, p. 361; 

see In re Viking Pump, Inc. (2016) 27 N.Y.3d 244, 266 [52 N.E.3d 

1144, 1157] [holding that “other insurance” clauses do not 

mandate horizontal exhaustion under all sums allocation, and 

explaining that “ ‘other insurance’ clauses ‘apply when two or 

more policies provide coverage during the same period, and they 

serve to prevent multiple recoveries from such policies’ . . . .

[O]ther insurance clauses are not implicated in situations 

involving successive—as opposed to concurrent—insurance 

policies”]; see also Steadfast Insurance Co. v. Greenwich Ins.

(2019) 385 Wis.2d 213, 228 [922 N.W.2d 71, 79] [“ ‘The accepted 

meaning of “other insurance” provisions does not include

application to successive insurance policies.’ ”]; Ohio Cas. Ins. 

Co. v. Unigard Ins. Co. (Utah 2012) 268 P.3d 180, 184 [“ ‘[O]ther 

insurance’ provisions do not apply to successive insurers.”]; 

Boston Gas Co. v. Century Indem. Co. (2009) 454 Mass. 337, 361
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

21

[910 N.E.2d 290, 308] [“ ‘[O]ther insurance’ clauses simply 

reflect a recognition of the many situations in which concurrent, 

not successive, coverage would exist for the same loss.”]; 

Benjamin Moore & Co. v. Aetna Cas. (N.J. 2004) 843 A.2d 1094, 

1101 [“ ‘[O]ther insurance’ clauses, which are provisions 

typically designed to preclude a double recovery when multiple, 

concurrent policies provide coverage for a loss[,] . . . [are] not 

generally applicable in the continuous-trigger context where 

successive rather than concurrent policies [are] at issue.”].) 

Given the generally understood purpose of “other insurance” 

clauses, it is difficult to read the clauses here as a clear and 

explicit direction to adopt a requirement of horizontal 

exhaustion in cases of long-tail injury.

While the “other insurance” clauses do not speak clearly 

to the question before us, other aspects of the insurance policies 

strongly suggest that the exhaustion requirements were meant 

to apply to directly underlying insurance and not to insurance 

purchased for other policy periods. First and most obviously, 

the excess policies explicitly state their attachment point, 

generally by referencing a specific dollar amount of underlying 

insurance in the same policy period that must be exhausted. For 

example, certain Fireman’s Fund Insurance Company policies 

provide: “It is a condition of this policy that the insurance 

afforded under this policy shall apply only after all underlying 

insurance has been exhausted.” The policies then list the 

“Underlying Insurance Limit of Liability”—for example, 

“$30,000,000 each occurrence $30,000,000 aggregate.” In other 

words, this policy agrees to indemnify Montrose once it has 

exhausted $30 million of underlying insurance. But under the 

insurers’ theory of horizontal exhaustion, Montrose would not 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

22

be permitted to access this policy until it has exhausted $30 

million of underlying insurance for every relevant policy period—

which would add up to substantially more than $30 million. 

Indeed, here, where the continuous injury occurred over the 

course of a quarter century, such a rule would increase the 

operative attachment point for this policy from $30 million to 

upwards of $750 million. Thus, where aggregate liability 

amounts to approximately $200 million, Montrose would not be 

able to access an insurance policy that, by its terms, kicks in 

after $30 million of underlying insurance is exhausted.

Relatedly, the excess policies regularly include or 

reference schedules of underlying insurance—all for the same 

policy period. Under Montrose’s reading, these schedules 

provide a presumptively complete list of insurance coverage that 

must be exhausted before the excess policy may be accessed, 

with the “other insurance” clauses serving as a backstop to 

prevent double recovery in the rare circumstance where 

underlying coverage changes after the excess policy is written. 

(See Dart, supra, 28 Cal.4th at p. 1079.) But under the insurers’ 

rule of horizontal exhaustion, these schedules would represent 

only a fraction—perhaps only a small fraction—of the insurance 

policies that must be exhausted before a given excess policy may 

be accessed. 

In sum, the “other insurance” clauses do not clearly specify 

whether a rule of horizontal or vertical exhaustion applies here. 

Read in isolation, the “other insurance” clauses might plausibly 

be read to perform the function the insurers ascribe to them. 

But read in conjunction with the actual language of other 

provisions in the policies, and in light of their historical role of 

governing allocation between overlapping concurrent policies, 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

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the insurers’ reading becomes less likely. Rather, in the absence 

of any more persuasive indication that the parties intended 

otherwise, the policies are most naturally read to mean that 

Montrose may access its excess insurance whenever it has 

exhausted the other directly underlying excess insurance 

policies that were purchased for the same policy period.

C.

To the extent any of the language of these policies remains

ambiguous, we resolve these ambiguities to protect “ ‘ “ ‘the 

objectively reasonable expectations of the insured.’ ” ’ ” 

(Minkler, supra, 49 Cal.4th at p. 321.) Consideration of the 

parties’ reasonable expectations favors a rule of vertical 

exhaustion rather than horizontal exhaustion.

For starters, applying the horizontal exhaustion rule 

would be far from straightforward. The insurers describe the 

rule in simple terms: as a matter of traveling across “layers” of 

stacked “blocks” of excess insurance coverage before the insured 

may travel upwards. But this depiction suggests a degree of 

standardization across policies that does not exist. The policies 

Montrose purchased come in all shapes and sizes, each covering 

different periods of time, providing different levels of coverage, 

and setting forth distinct exclusions, terms, and conditions. 

Given all of these variations across the relevant dimensions, 

how would a rule of horizonal exhaustion apply? If one were to 

stack the excess policies on a graph based on their coverage 

limits or attachment points, the first layer of excess insurance 

in 1984, for example, would appear to reach as high as the 13th 

layer of excess coverage in 1974. To which horizontal layer does 

the 1984 policy belong? The policies do not say. Nor does 

anything in the text of these policies tell us how an “other 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

24

insurance” clause in a policy from one period ought to apply to a 

policy from another period that contains both a lower 

attachment point and a higher coverage limit. The policies’ 

silence on these basic, foundational questions tends to 

undermine the idea the parties expected such a rule to apply.

But perhaps more importantly, because the exclusions, 

terms, and conditions may vary from one policy to another, a 

rule of horizontal exhaustion would create significant practical 

obstacles to securing indemnification. As the Court of Appeal 

stated in State of California v. Continental Ins. Co., supra, 15 

Cal.App.5th at page 1033, “if a lower-layer insurer for a different 

policy period happened to claim that some exclusion in its policy 

applied, a court could not determine whether Continental’s 

policies were triggered without first determining that exclusion 

claim.” Such a rule would put the insured to the considerable 

expense of establishing a right to coverage under the definitions, 

terms, conditions, and exclusions from policies in every policy 

period triggered by the continuous injury. Coverage under less 

restrictive policies would be delayed until more restrictive policy 

terms are adjudicated. In sum, “[h]orizontal exhaustion would 

create as many layers of additional litigation as there are layers 

of policies.” (Westerport Ins. Corp. v. Appleton Papers Inc.

(Wis.Ct.App. 2010) 787 N.W.2d 894, 918.) What is more, 

requiring a policyholder to litigate the terms and conditions of 

all policies with lower attachment points in every policy period 

before accessing policies with higher attachment points would 

effectively increase the attachment point—thereby 

undermining the policyholder’s reasonable expectation that 

coverage would be triggered upon the exhaustion of the amount 

listed as the policy’s stated attachment point. Objectively 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

25

speaking, the parties could not have intended to require the 

insured to surmount all these hurdles before the insured may 

access the excess insurance it has paid for.

The insurers counter that the rule of horizontal 

exhaustion is logically compelled by our adoption of an all-sumswith-stacking approach to liability for long-tail injuries. They 

argue that if the insured is to have access to all policies across 

all relevant policy periods, it only makes sense that the insured 

must seek indemnification based on its excess coverage across 

all relevant policy periods; to do otherwise, the insurers assert,

would “artificially break[]” the long-tail injury into distinct 

periods, contrary to our holding in Continental. (Continental, 

supra, 55 Cal.4th at p. 201.) But the insurers’ conclusion does 

not follow. A rule of vertical exhaustion does not restrict the 

insured from accessing excess coverage from other policy periods

if the terms and conditions are otherwise met; it merely relieves 

the insured of the obligation of establishing whether all of the 

applicable terms and conditions at any given “layer” of excess 

coverage are met before it accesses the next “layer” of coverage. 

There is no evident inconsistency between an all sums approach 

and one that avoids placing this burden on the insured, with its 

associated delays, before the insured may access its excess 

insurance.

But if horizontal exhaustion imposes a heavy burden on 

the insured, the insurers claim that vertical exhaustion is 

“totally unfair” to them because “decades’ worth of 

environmental damage [could] fall on the shoulders of 

disfavored insurers who happened to provide excess insurance

. . . during that single unlucky year or two.” This argument is 

not different in kind from arguments we have already 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

26

considered and rejected in adopting the all-sums-with-stacking 

approach to the coverage of long-tail injuries. (See, e.g., 

Continental, supra, 55 Cal.4th at pp. 199–200; id. at pp. 201–

202.) What we have said in prior cases applies here as well: 

There is no evident unfairness to insurers when their insureds

incur liabilities triggering indemnity coverage under the 

negotiated policy contract.7 Just as the all-sums-with-stacking 

approach allows the insured “immediate access to the insurance 

it purchased,” so, too, does vertical exhaustion in a continuous 

injury case. (Continental, at p. 201.)

Equally to the point, nothing about the rule of vertical 

exhaustion requires a single insurer to shoulder the burden of 

indemnification alone. As we explained in the context of 

primary insurance, “the obligation of successive primary 

insurers to cover a continuously manifesting injury is a separate 

issue from the obligations of the insurers to each other.” (Dart, 

supra, 28 Cal.4th at p. 1080.) Even though a rule of vertical 

exhaustion permits Montrose to access excess insurance from 

any given policy period, provided the directly underlying 

insurance has been exhausted, insurers may seek contribution 

from other excess insurers also liable to the insured. The 

exhaustion rule does not alter the usual rules of equitable 

contribution between insurers. An insurer required to provide 

excess coverage for a long-tail injury may lessen its burden by 

seeking reimbursement from other insurers that issued policies 

during the relevant period. Once again, the critical difference 

 

7 Whether losses may be partially allocated to the insured 

for policy periods in which the insured chose to self-insure is a 

question not presented here.
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

27

between a rule of vertical exhaustion and horizontal exhaustion 

thus is not whether a single disfavored excess insurer will be 

made to carry a disproportionate burden of indemnification, but 

instead whether the administrative task of spreading the loss 

among insurers is one that must be borne by the insurer instead 

of the insured. There is no obvious unfairness to insurers from 

a rule that requires them to bear this administrative burden.

The insurers lean heavily on Community Redevelopment 

Agency v. Aetna Casualty & Surety Co. (1996) 50 Cal.App.4th 

329, but that case addresses a meaningfully different scenario 

and thus offers no real lessons for resolving the question now 

before us. In Community Redevelopment, a primary insurer 

sought contribution from an excess insurer for defense costs on 

behalf of the insured in a case involving continuous loss. To 

resolve the conflict, the court applied what it termed a 

“horizontal exhaustion rule”; under that rule, the court held, an 

excess insurer in a continuous injury case is not required “to 

‘drop down’ and provide a defense to a common insured before 

the liability limits of all primary insurers on the risk have been 

exhausted.” (Id. at p. 332.) In adopting that rule, the court 

explained: “Absent a provision in the excess policy specifically 

describing and limiting the underlying insurance, a horizontal 

exhaustion rule should be applied in continuous loss cases 

because it is most consistent with the principles enunciated in 

Montrose [I, supra, 10 Cal.4th 645]. . . . Under the principle of 

horizontal exhaustion, all of the primary policies must exhaust 

before any excess will have coverage exposure.” (Community 

Redevelopment, at p. 340.)

This case differs from Community Redevelopment in 

fundamental respects. This case, unlike Community 
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Opinion of the Court by Kruger, J.

28

Redevelopment, is not a contribution action between primary 

and excess insurers; it is, rather, a coverage dispute between 

excess insurers and their insured. Regardless of whether 

Community Redevelopment was correct to apply a rule of 

horizontal exhaustion in that distinct context—a question not 

presently before us—we are unpersuaded that the reasoning of 

Montrose I requires us to apply a rule of horizontal exhaustion 

that would limit Montrose’s ability to access the excess 

insurance coverage it has paid for.

In sum, we conclude that in a case involving continuous 

injury, where all primary insurance has been exhausted, the 

policy language at issue here permits the insured to access any 

excess policy for indemnification during a triggered policy period 

once the directly underlying excess insurance has been

exhausted. Parties to insurance contracts are, of course, free to 

write their policies differently to establish alternative

exhaustion requirements or coverage allocation rules if they so 

wish. (See Continental, supra, 55 Cal.4th at p. 202.)

D.

As noted earlier, Travelers opposes Montrose’s motion for 

summary adjudication on two independent grounds. First, 

Travelers argues that Montrose’s requested declaration, which 

would permit Montrose to “seek indemnification” from an excess 

policy upon establishing that “its liabilities are sufficient to 

exhaust the underlying policy(ies) in the same policy period,” is 

directly contrary to the terms of the Travelers policies, which 

require actual exhaustion before a policyholder may access 

excess coverage. Second, Travelers argues that its policies with 

Montrose must be construed under Connecticut or New York 

law, rather than California law as assumed by Montrose’s 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

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Opinion of the Court by Kruger, J.

29

petition, given Montrose’s principal place of business at the time 

the Travelers policies were issued. The lower court did not reach 

either of these issues because it determined for other reasons 

that Montrose is not entitled to summary adjudication. 

(Montrose II, supra, 14 Cal.App.5th at p. 1336, fn. 9.)

These arguments are not properly before us. We granted 

Montrose’s petition to determine whether Montrose may seek 

coverage from its excess policies under a rule of vertical 

exhaustion rather than horizontal exhaustion. The choice 

between these two rules does not alter any of the remaining 

prerequisites Montrose must satisfy to obtain indemnification, 

including actual exhaustion of directly underlying insurance, 

according to the specific terms of its excess policies. And because

the lower courts have not addressed the competing claims about 

choice of law, we decline to resolve the matter in the first 

instance. (See Guz v. Bechtel National Inc. (2000) 24 Cal.4th 

317, 348.) Whether California law governs the construction of 

Montrose’s policies with Travelers is a question for the Court of 

Appeal on remand.

III.

California law permits Montrose to seek indemnification 

under any excess policy once Montrose has exhausted the

underlying excess policies in the same policy period. Montrose 

is not required to exhaust excess insurance at lower levels for 

all periods triggered by continuous injury before obtaining 
MONTROSE CHEMICAL CORPORATION OF CALIFORNIA 

v. SUPERIOR COURT

Opinion of the Court by Kruger, J.

30

coverage from higher level excess insurance in any period. We

reverse the judgment of the Court of Appeal and remand for 

further proceedings consistent with this opinion.

KRUGER, J.

We Concur:

CANTIL-SAKAUYE, C. J.

LIU, J.

CUÉLLAR, J.

GROBAN, J.

ELIA, J.*

BROWN, J.**

 

* Associate Justice of the Court of Appeal, Sixth Appellate 

District, assigned by the Chief Justice pursuant to article VI, 

section 6 of the California Constitution.

** Associate Justice of the Court of Appeal, First Appellate 

District, Division Four, assigned by the Chief Justice pursuant 

to article VI, section 6 of the California Constitution.
See next page for addresses and telephone numbers for counsel who argued in Supreme Court.

Name of Opinion Montrose Chemical Corp. v. Superior Court 

__________________________________________________________________________________

Unpublished Opinion

Original Appeal

Original Proceeding 

Review Granted XXX 14 Cal.App.5th 1306

Rehearing Granted

__________________________________________________________________________________

Opinion No. S244737

Date Filed: April 6, 2020 

__________________________________________________________________________________

Court: Superior

County: Los Angeles

Judge: Elihu Berle

__________________________________________________________________________________

Counsel:

Latham & Watkins, Brook B. Roberts, John M. Wilson and Drew T. Gardiner for Petitioner.

Morgan Lewis & Bockius, Michel Y. Horton, Jeffrey S. Raskin, Thomas M. Peterson, Paul A. Zevnik 

and David S. Cox for ITT LLC and Santa Fe Braun, Inc., as Amici Curiae on behalf of Petitioner.

No appearance for Respondent.

Gibson, Dunn & Crutcher, Theodore J. Boutrous, Jr., Julian W. Poon, Jeremy S. Smith and Madeleine F. 

McKenna for Real Parties in Interest Continental Casualty Company, Columbia Casualty Company, 

American Centennial Insurance Company and Lamorak Insurance Company.

Sinnott, Puebla, Campagne & Curet, Kenneth H. Sumner and Lindsey A. Morgan for Real Parties in 

Interest AIU Insurance Company, American Home Assurance Company, Granite State Insurance 

Company, Landmark Insurance Company, Lexington Insurance Company, National Union Fire Insurance 

Company of Pittsburgh, PA, and New Hampshire Insurance Company.

Sinnott, Puebla, Campagne & Curet, Randolph P. Sinnott, Mary E. Gregory; Cozen O'Conner and John 

Daly for Real Party in Interest Zurich International (Bermuda) Ltd.

Duane Morris, Max H. Stern and Jessica E. La Londe for Real Party in Interest American Centennial 

Insurance Company.

Craig & Winkelman and Bruce H. Winkelman for Real Party in Interest Munich Reinsurance America, Inc.

Selman & Breitman, Ilya A. Kosten, Kelsey C. Start; Barbanel & Treuer and Alan H. Barbanel for Real 

Parties in Interest Transport Insurance Company and Lamorak Insurance Company.

Selman & Breitman and Elizabeth M. Brockman for Real Party in Interest Federal Insurance Company.

Berkes, Crane, Robinson & Seal, Steven M. Crane and Barbara S. Hodous for Real Parties in Interest 
Continental Casualty Company and Columbia Casualty Company.

Lewis Brisbois Bisgaard & Smith, Peter L. Garchie and James P. McDonald for Real Party in Interest 

Employers Mutual Casualty Company.

Barber Law Group and Bryan M. Barber for Real Party in Interest Employers Insurance of Wausau.

McCurdy & Fuller, Kevin G. McCurdy and Vanci Y. Fuller for Real Parties in Interest Everest Reinsurance 

Company and MT. McKinley Insurance Company.

Chamberlin & Keaster, Chamberlin Keaster & Brockman, Kirk C. Chamberlin, Michael

Denlinger and Kevin J. Schettig for Real Party in Interest Providence Washington Insurance Company.

Tressler, Linda Bondi Morrison and Ryan B. Luther for Real Party in Interest Allstate Insurance Company.

Archer Norris, Andrew J. King, GailAnn Y. Stargardter; Tressler and Charles R. Diaz for Real Parties in 

Interest Fireman's Fund Insurance Company and National Surety Corporation.

Lewis, Brisbois, Bisgaard & Smith, Jordon E. Harriman, Shannon L. Santos; Budd Larner and Michael J.

Balch for Real Parties in Interest General Reinsurance Corporation and North Star Reinsurance 

Corporation.

Hinshaw & Culbertson, Thomas R. Beer and Peter J. Felsenfeld for Real Party in Interest Gerling Konzern 

Allgemeine Versicherungs-Aktiengesellschaft.

O'Melveny & Myers, Richard B. Goetz, Zoheb P. Noorani and Michael Reynolds for Real Party in Interest 

TIG Insurance Company.

McCloskey, Waring, Waisman & Drury and Andrew McCloskey for Real Party in Interest 

Westport Insurance Corporation.

Simpson Thacher & Bartlett, Peter R. Jordon, Andrew T. Frankel, Deborah Lynn Stein and Tyler Z.

Bernstein for Real Parties in Interest Travelers Casualty and Surety Company and The Travelers Indemnity 

Company.

Covington & Burling, David B. Goodwin, Reynold L. Siemens, Jeffrey A. Kiburtz and Heather W. Habes 

for United Policyholders as Amicus Curiae on behalf of Petitioner.
Counsel who argued in Supreme Court (not intended for publication with opinion):

John Wilson

Latham & Watkins LLP

12670 High Bluff Drive

San Diego, CA 92130

(858) 523-5400

Theodore J. Boutrous, Jr.

Gibson, Dunn & Crutcher, LLP

333 South Grand Avenue

Los Angeles, CA 90071

(213) 229-7500