LOST REFERENTIAL INTEGRITY

Referential Integrity on one of our production tables seems to have been
lost.  I am running Postgres 7.1.3 embedded within Red Hat
kernel-2.4.9-e.49.

Within that I have a table with referential integrity constraints which
no longer work.

I do not know how to disable referential integrity on a column in a table.

I do not know how to view what Postgres thinks my referential integrity
constraints are on this table.
I do ...-c"\d table_with_referential_integrity" and here's what I get:

[~]$ mpt -c"\d pat_emp_ins"
            Table "pat_emp_ins"
      Attribute             |  Type   | Modifier
---------------------------+-----------+----------
 pat_id                        | text       | not null
 ins_co_id                   | text       | not null
 employer_id              | text       | not null
 insurance_group        | text       |
 note                            | text       |
 print_note_primary   | boolean |
 print_note_secondary | boolean |
Indices: pat_emp_ins_employer_id_key,
         pat_emp_ins_ins_co_id_key,
         pat_emp_ins_pat_id_key

[~ create_tables_for_database]$

And here is the SQL I used to generate this table:

--
   create table pat_emp_ins (pat_id               text not null

references patient,
                             ins_co_id                          text not
null

references insurance_company,
                             employer_id                     text not null

references employer,
                             insurance_group              text,
                             note                                  text,
                             print_note_primary         boolean,
                             print_note_secondary      boolean,
                             unique(pat_id,ins_co_id,employer_id));
--

Problem is, my users using my application are able to insert rows into
"pat_emp_ins" table which have values for "employer_id" and/or
"ins_co_id" which do not exist in the referenced tables.  This seems to
have happened recently but I do not know how recently.  This application
has been running production since 2003-11-07.