use strict;
use warnings;

my @strings = ( '/lawyers/stuffLDSstuff/~Firms.html',
                '/lawyers/stuffnotstuff/~Firms.html' );
                
foreach my $string ( @strings ) {
    print $string;
    if( $string =~ m#/lawyers/(?!.*LDS).*~Firms\.html# ) {
        print " matches.\n";
    } else {
        print " doesn't match.\n";
    }
}