Non-Cumulation and Prior Insurance Clauses: Allocating Liability Among Multiple Policies Triggered by Multi-Year Loss

Application of Non-Cumulation Clauses in Pro Rata vs. All Sums Jurisdictions

Recording of a 90-minute CLE webinar with Q&A

Conducted on Thursday, January 12, 2017

Recorded event now available

or call 1-800-926-7926
Program Materials

This CLE webinar will update insurance counsel on the latest developments in the application of non-cumulation provisions in CGL policies to deny coverage in long-tail claims. The panel will outline best practices for counsel to insureds or insurers to argue for maximizing coverage or minimizing liability.


One of the most complex issues in insurance coverage disputes involves long-tail claims—such as asbestos bodily injury and environmental claims. Such claims raise complex questions of how liabilities should be allocated among numerous policy years triggered by such losses.

Insurers seek to minimize or eliminate the obligation to pay long-tail claims by arguing that the “Prior Insurance and Non-Cumulation of Liability Clause” shifts responsibility for paying for losses that trigger multiple policy years to triggered policies issued prior to their own policy year.

Policyholders argue that non-cumulation clauses are ambiguous as there are a host of unresolved coverage questions that arise in the context of attempting to apply such clauses to long-tail claims.

Listen as our authoritative panel of insurance practitioners guides you through an analysis of non-cumulation clauses in CGL policies and the various ways courts have interpreted these clauses.



  1. Background in which non-cumulation clauses are interpreted and applied
    1. Typical policy language
    2. London version of clause
    3. Triggers of coverage
    4. Allocation
  2. Court interpretations and applications of non-cumulation clauses
    1. Pro rata jurisdictions
    2. All sums jurisdictions
    3. Reduction, but not elimination of insurer’s payment obligation
  3. Applicable insurance policy interpretation principles
    1. Contra proferentem
    2. Reasonable expectations doctrine
    3. Construction of policy as a whole


The panel will review these and other key issues:

  • How are triggers of coverage and allocation methods impacted by non-cumulation clauses?
  • How have courts in pro rata versus all sums jurisdictions differed in their interpretations and applications of non-cumulation clauses?
  • What insurance policy construction principles are applicable in interpreting non-cumulation clauses?


Borja, Mary
Mary E. Borja

Wiley Rein

Ms. Borja represents insurers in complex litigation and arbitration involving professional liability, general...  |  Read More

Sherilyn Pastor
Sherilyn Pastor

McCarter & English

Ms. Pastor is the Practice Leader of the firm’s Insurance Coverage Group. She has secured hundreds of millions of...  |  Read More

French, Christopher
Christopher C. French

Visiting Assistant Professor of Law
Penn State Law School

Professor French teaches contracts, torts, civil procedure and insurance law. He has written and published extensively...  |  Read More

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